Paper - How Large is the Mammalian Egg?: Difference between revisions
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=How Large is the Mammalian Egg? A Review= | |||
By Carl G. Hartman | |||
Department of Embryology, Carnegie Institution of Washington, Betltimare, Mn. | |||
If one sketch the outline of a hen's | |||
egg so as to fill a page of this Journal | |||
as nearly as possible, the egg of the | |||
oviparous Australian mammal Ornitiiorbynclnm, drawn to the same scale, would | |||
be represented by the natural size of the | |||
hen's egg, the entire opossum egg with | |||
its albumen, by a cross-section of the lead | |||
in a pencil, the human egg by a period in | |||
average sized type. | |||
Within the phylum Vertebrate; the differences between the smallest eggs, those of | |||
mammals, and the largest is even greater. | |||
Thus the eggs of certain “man-eating" | |||
sharks (Lamnids) are as much as 2.2.0 mm. | |||
in diameter. The egg shell of the now | |||
exterminated Apyorni: measured 350 mm. | |||
or over a foot in its longest diameter. The | |||
ostrich egg is -150 mm. in length and has a | |||
capacity of 1.2 liters, or over aquart. | |||
In the evolution of mammals, the | |||
Monotremes (Omitlaorbyncbn: and Ecbidnn) | |||
form an interesting link, for they possess | |||
in their hairy covering and milk secreting | |||
glands the chief distinguishing class characteristics of mammals. Yet they “lay" | |||
large yolk-laden eggs from which the | |||
young emerge after a short incubation | |||
outside the female's body. From the | |||
15-millimeter egg of Ornitborlqynclms and | |||
the 15-millimeter egg of Ecbidnet there is a | |||
sudden drop to the typical mammalian | |||
egg, which measures about one-tenth of a | |||
millimeter. It is true that the marsupial | |||
eggs show some transitional characters, as for example, the large albumen layer, | |||
the shell membrane, and a somewhat | |||
richer supply of yolk, as in Dnsyuru: | |||
(Hill). But throughout the Eat/aeriez, the | |||
mammals above the marsupials, the egg is | |||
very uniform, with not much over a twoto-one variation in size (table 8), which | |||
holds from rat to man, from bat to horse, | |||
from mouse to elephant and whale. The | |||
size of the animal bears no relation to -the | |||
size of the egg. | |||
The comparison between the large yolkladen eggs on the one hand and the human | |||
egg or the eggs of most mammals on the | |||
other is not fair to the latter group, for | |||
these represent only the yolk or "vitellus" | |||
of larger eggs. The total diameter of the | |||
hen's egg, for example, is due largely to | |||
the albumen laid down in the oviduct | |||
around the vitellus. The human egg has | |||
no such envelope, and this is true of all | |||
mammals with the exception of the | |||
marsupials and the Lagomorpha (hares | |||
and rabbits). Thus the egg of our only | |||
marsupial, the opossum, has a thick albumen layer enclosed in a thin shell membrane; the rabbit egg lacks the shell membrane, while all other mammalian eggs | |||
have only a highly transparent limiting | |||
membrane, or “zona pellucida," which | |||
they receive in the ovary before their discharge into the oviduct. The opossum | |||
egg, with its opaque white ovum proper | |||
in the center of a transparent, hardly | |||
visible albumen sphere, looks, in reflected light, much like a grain of sago not quite | |||
cooked through—a hyaline sphere with a | |||
white spherule in the center. | |||
This comparison between the egg of | |||
fowl and that of mammals must be controlled in another way. The yolk or | |||
vitellus of the hen's egg is so laden with | |||
fat and protein pabulum for the developing | |||
embryo that the egg nucleus, with its | |||
associated tiny mass of protoplasm, which | |||
alone will make the chick embryo, becomes all but lost on the surface of the | |||
yolk. But that speck of protoplasm corresponds to the entire Eutherian egg. The | |||
reduction in size has, of course, been | |||
made possible by the parasitic habit assumed by the mammalian fetus through | |||
implantation in the maternal tissues. | |||
In order to visualize for himself the | |||
actual size of the mammalian egg, the | |||
reader may follow the suggestion which | |||
the Berlin anatomist Waldeyer was wont | |||
to give his students. Spread out, said he, | |||
a sample of sand on a sheet of paper, brush | |||
off the easily visible grains and pick out | |||
the smallest grain, which it is just possible | |||
to see with the naked eye—that speck is | |||
of the order of magnitude of the mammalian egg. | |||
THE DISCOVERY OF THE MAMMALIAN EGG | |||
In view of the small size of the mammalian egg, it is not at all surprising that | |||
it so long escaped detection. It was not | |||
until 182.7 that von Baer announced the | |||
discovery of the real mammalian and | |||
human eggs. From the time of de Graaf | |||
(1673) to that of von Baer the large | |||
vesicular follicle of the ovary was regarded as the egg. We now know that | |||
the ovarian follicles that bear de Graaf’s | |||
name do not constitute the egg but contain | |||
the egg. The clear, limpid “graafian” | |||
follicles in the ovary of the rabbit, before | |||
their dehiscence, do greatly resemble eggs | |||
of about eight days’ development, but how such large eggs were to pass through | |||
the narrow lumen of the oviduct did not, | |||
it seems, concern many investigators. I | |||
read, however, in Ritchie's interesting | |||
book, Contribution; to Assist the Study of | |||
Ovarian Physiology and Pathology (1865) | |||
that Morgagni, in his Aoloermria Anatomim Omnia (1741) made the following | |||
reflections: “How much more likely is | |||
the conjecture that they (the ovarian | |||
follicles) are glands secreting fluid for the | |||
purpose of keeping the ovum safe, and | |||
helping it to escape when the proper | |||
time arrives." The error referred to | |||
above was a costly one and doubtless | |||
retarded progress in the study of embryology during the century preceding von | |||
Baer. It is interesting to note that Jones | |||
(1837) varied the error of deGraaf by | |||
confusing the gelatinous envelope of the | |||
rabbit egg with the liquor folliculi. | |||
However, the century following the | |||
“Father of Embryology,” the nineteenth, | |||
did not produce a large array of investigators who occupied themselves with the | |||
study of the early stages of the mammalian | |||
egg. Without a doubt the outstanding | |||
figure was Bischoff, who published, in | |||
the forties and following decades, his | |||
classical studies on the rabbit, the dog, | |||
the guinea-pig, and other domestic | |||
animals, as also the deer. These studies | |||
have stood the test of time; Bischoff's | |||
measurements on the living eggs were the | |||
most extensive up to a very recent date. | |||
My calculations of Bischoff’s data are uniformly | |||
too high. I have followed Keibel’s equivalent of 3 | |||
Prussian Inches (R2,) the equal of 80 mm. This | |||
approximates our equivalent of 2.5 mm. for one inch. | |||
Thus the average given for the dog egg (1845, page 7) | |||
is o.oo68 to o.oo7o P.Z. or 1/13 to 1/12. P.L. or 16 to | |||
19/ I00 mm. These dimensions in Iuicra, according to | |||
my calculations would be: 181 to 186, 170 to 184, | |||
166 to 190. It seems that Bischoff attempted exact’ness only in terms of decimal fractions of the P.Z. | |||
(preussischer Zoll.). Since his measurements run | |||
pretty uniform though high it is probable that the unit of measurement he used was smaller than he | |||
thought by a small fraction. | |||
Sobotta (1895) studied 1459 mouse eggs | |||
in maturation and early cleavage, and | |||
Long and Mark (1911) I000 mouse eggs in | |||
maturation and fertilization. These constitute the most extensive studies of a | |||
single species and on a limited phase of | |||
development, but they do not include a | |||
single measurement on the living egg. | |||
As will be pointed out herein, it is the | |||
living egg alone that affords the true | |||
TABLE I | |||
Frem Long and Marie (1911), rbowing change: in size of | |||
tin: mam: egg during maturation and fertilization, | |||
bared on egg: fixed in Jim | |||
AVERmm— D‘;;’:_ | |||
STAGE BEEéIG0sF BER | |||
mom | |||
Ovarian: | |||
Germinal vesicle . . . . . . . . . . . . . . . . . . 109 65 5 | |||
Beginning of first maturation division . . . . . . . . . . . . . . . . . . . . . . . . . . 53 62.5 | |||
first maturation division . . . . . . . . . . . 7.11 58.0 | |||
Tubal.Second spindle . . . . . . . . . . . . . . . . . . . 507 55 .6 | |||
Second maturation division . . . . . . . . . 36 53 .6 | |||
Pronuclei . . . . . . . . . . . . . . . . . . . . . . . . . 17.3 54.0 | |||
Eggs in oviduct 16% hours . . . . . . . . . 5o 53 .3 | |||
Eggs in oviduct 7.9 hours . . . . . . . . . . . 50 56 .5 | |||
picture of the egg as a whole and it is only | |||
recently that such studies have gotten | |||
under Way. This fact does not, however, | |||
minimize the fundamental processes in | |||
the behavior of the egg which only | |||
microscopic preparations can disclose; for | |||
stained preparations have taught us about | |||
the significant behavior of the chromatin, | |||
the chief bearer of hereditary characters. | |||
SHRINKAGE OF THE TUBAL EGG | |||
Can we state in definite figures, then, | |||
with reasonable accuracy, the dimensions | |||
of the ovum in each species of mammal thus far studied? Before answering this | |||
question We must further define it. In the | |||
first place, We must specify the stage of | |||
development considered, for manifestly, | |||
sooner or later, the egg begins to grow. | |||
In this discussion We shall limit ourselves | |||
to the one-celled or undivided stage, or at | |||
least to the stage of early cleavage. | |||
These alone approximate the freshly discharged egg. Now there is considerable | |||
evidence in the literature that the nuclear | |||
changes of first maturation division in the | |||
ovary, the second division, and fertilization after ovulation involve also changes | |||
in the size of the egg, even entirely aside | |||
TABLE 2. | |||
Size: (in micra) of ovarian and tubal egg: calculated by the | |||
prerent writer from tbe atla: of van der Striebt | |||
(1923) amlfram /air ltat paper (1909) | |||
OVARIAN TUBAL | |||
“““‘“‘ aces mas | |||
Man . . . . . . . . . . . . . . . . . . . . . . . . . 141)(1I3 | |||
Dog . . . . . . . . . . . . . . . . . . . . . . . . .. IIIX97. xo2.)(87 | |||
Cat . . . . . . . . . . . . . . . . . . . . . . . . .. 95x84 81 X77. | |||
Guinea pig . . . . . . . . . . . . . . . . . . . 77x63 63x58 | |||
Bat (197.3) . . . . . . . . . . . . . . . . . . .. 95 X78 7oX65 | |||
Bat (1909) . . . . . . . . . . . . . . . . . . .. 9o><69 66X58 | |||
Mouse . . . . . . . . . . . . . . . . . . . . . .. 8oX62. 53x53 | |||
from the small mass of cytoplasm and | |||
nuclear material extruded with the polar | |||
bodies. Long and Mark state that a | |||
maximal size of the egg is reached at the | |||
end of the so-called period of growth, | |||
while the egg nucleus is in the condition | |||
of a vesicle. From this time to fertilization there is a progressive slight shrinkage, after which the egg increases in size | |||
with its sojourn in the tube. Long and | |||
Mark's figures are quoted in Table I | |||
because they are unique in the number of | |||
eggs measured and the care with which | |||
the work was done. | |||
Lams and Doorme (1907) were probably the first to call attention to this | |||
phenomenon, which 0. Van der Stricht, | |||
their teacher, believed to be quite general | |||
for mammalian eggs. This author also | |||
believed that the low- point varies in | |||
different mammals, but in view of the | |||
condition of the material on which he | |||
made his measurements We may well | |||
doubt that so nice a point could have been | |||
determined‘ by him. That the ovarian | |||
egg is generally reported to be larger than | |||
the tubal egg there is no doubt, as one | |||
can readily see by a study of the literature. | |||
Sobotta in 1905 set down the mouse egg | |||
at 59 micra for both the ovarian and the | |||
tubal stages, but in a later paper he granted | |||
65 to 70 micra to the ovarian, 60 to the | |||
tubal ovum. From Van der Stricht's | |||
extensive data I have calculated Table 7., | |||
from the standpoint of the present comparison. This author's paper of 197.3 | |||
constitutes a veritable atlas of the early | |||
history of the mammalian egg, based on | |||
the most extensive and varied series in | |||
the world. | |||
A similar excess in size of ovarian over | |||
tubal ova I have reported for the opossum, | |||
where, however, the former were measured | |||
in situ, the latter after being washed | |||
from the tube and studied singly. Other | |||
data in the literature were mostly based | |||
on material fixed and sectioned, usually in | |||
situ. The measurements are thus open to | |||
objection; both ovarian and tubal eggs | |||
should be studied alive in the same | |||
medium. This I have done in the case of | |||
the rabbit. Ovarian eggs removed from | |||
the right ovary, excised surgically seven | |||
hours post coitum, measured on the average 17.7. x 119 micra. Nineteen hours | |||
later two eggs Were taken from the left | |||
fallopian tube; they were in the two-celled’ | |||
stage when removed, but divided again | |||
and were four-celled before they could be | |||
photographed. They measured 12.4 X 17.4 | |||
micra, a little larger than the ovarian | |||
eggs. Dr. W. H. Lewis killed a rabbit | |||
ten hours post coitum, when some of the eggshad been shed while others were still | |||
retained in the follicles. One ovarian | |||
egg measured 119, the other 133 micra; | |||
the average for tubal ova was 17.4 micra. | |||
The progressive changes in size of the | |||
mammalian egg, therefore, await more | |||
extensive study. This Will be made by | |||
better methods in connection with other | |||
studies on the egg. | |||
SHRINKAGE DUE TO fiXATION | |||
The size changes incident to- the vital | |||
activities of the developing egg, as set | |||
forth above, become insignificant when | |||
compared with the shrinkage caused by | |||
fixing agents and the after-treatment used | |||
in making microscopic preparations. | |||
Hence we must know under what conditions the eggs are measured. Since the | |||
introduction, about 1870, of the paraffin | |||
method of section cutting, by which an | |||
egg one—tenth of a millimeter may readily | |||
be cut into ten or more sections of convenient thickness, the tendency to use the | |||
method on all occasions has been overdone, for it has been substituted for the | |||
older and, for some purposes, better | |||
method of studying the object in the living | |||
state. Refined technique has often been | |||
made an end in itself, rather than an aid. | |||
fixing fluids, too, cause a variable amount | |||
of shrinkage, those containing osmic acid | |||
the least of all. The rate at which the | |||
reagents are changed is another important | |||
factor. With the most careful treatment | |||
the Writer kept the shrinkage down, for | |||
the most part, to about 15 per cent; more | |||
speed in handling the material would certainly have resulted at times in a 30 per | |||
cent shrinkage, which is not unusual in | |||
much of the work published on the | |||
mammalian egg. The study of the mouse | |||
egg might be cited in this connection. | |||
Sobotta (1905) gives 59 micra for the | |||
average mouse egg fixed in either ovary or | |||
tube, but in a later paper states that 65 to 70 micra is nearer the truth for the ovarian | |||
egg. Kirkham (1907), basing his measurements on the living egg, gives 80 micra | |||
for the ovarian, 73 to 78 for the tubal egg. | |||
The writer recently photographed five | |||
ovarian eggs of a field mouse (sp. 2‘) and | |||
these averaged 95 micra in diameter. It | |||
is therefore evident (and on this point | |||
there is no disagreement among the little data. The proneness of authors to | |||
let the reader make the calculations for | |||
himself is illustrated by Van der Stricht's | |||
invitation (192.3, page 2.79): “I shall not | |||
speak further about the exact dimensions | |||
of the eggs [he had not yet given any | |||
‘exact dimensions’]—it is easy to calculate | |||
them from the drawings.” This invitation I have. accepted, as did Corner | |||
TABLE 3 | |||
Measurment: made from photograph: of mammalian egg: taken in the living state. Negative: on file at the Carnegie | |||
Laboratory of Embryology, Baltimore. Diameter of o1/am proper (oitellm) or inner diameter of | |||
zona. Dimem-ion: in miera | |||
ANIMAL STAGE "U32: 01' AVERAGE SIZE INVESTIGATOR | |||
Rabbit 1-4-celled 6 12.6 Gregory | |||
Early cleavage 2.2. 12.4 Lewis | |||
Ovarian 1 119 Lewis | |||
Ovarian 1 133 Lewis | |||
Ovarian 5 12.o Hartman | |||
2.—4—celled 2. 12.4 Hartman | |||
Mouse Ovarian 5 95 Hartman | |||
Dog 1-celled tubal 3 12.0 Hartman | |||
Pig 1-celled tubal 4 111 Heuser and Streetet | |||
Cleavage 8 12.1 Heuser and Streeter | |||
Opossum 56 1-celled tubal 2. 145 Heuser and Hartman | |||
313 1-celled tubal 2. 12.6 x 1o6 Heuser and Hartman | |||
351 1-celled tubal 11 108 x 1oo Heuser and Hartman | |||
336, 337 Cleavage 6 151 x 140 Heuser and Hartman | |||
842. Early tubal 7 157 x 152. Hartman | |||
833 1-celled tubal 2. 173 Hartman | |||
766 Uterine 1 141 Hartman | |||
Various litters of Uterine 100 155 Hartman | |||
opossum | |||
authorities) that the fixed egg is no | |||
criterion of normal size of the living, | |||
functioning egg. | |||
A further complication is encountered | |||
if one attempts to calculate the size of eggs | |||
from authors’ illustrations where the | |||
magnifications are indicated. Articles | |||
that fail to indicate magnifications are, | |||
of course, of no avail for the purpose of | |||
this study (e.g., Rein, Melissinos). Were | |||
we to refrain entirely, however, from | |||
making calculations from the illustrations | |||
in the literature, there would remain jolly | |||
(CoWdry’s "Special Cytology,” volume | |||
II, page 1112.). The results must, however, fall somewhat short of the true | |||
diameter of even the fixed egg, for sections | |||
are selected that pass through features of | |||
interest, namely the egg nucleus, division | |||
spindle, and polar bodies. If these landmarks happen to fall in the middle section | |||
of the series the section fairly represents | |||
the act ual size of the egg; if, on the other | |||
hand, the section is a tangential one, the | |||
egg is actually larger than the section | |||
shows it to be. It is therefore apparent | |||
TABLE 4 | |||
Egg: (vitelle: only, or inner diameter of (ma) meamred in prepared section: affixed ovaries. Size: in micra | |||
ANDIAL AUTHORITY IMAXIMUM MINIMUM AVERAGE REMARKS | |||
Dasyurus Hill, 1911 7.70 x 7.60 7.80 x 17.6 7.40 Stated | |||
Didelpbis aurita Hill, 1918 — — 147. x 17.9 Stated | |||
Didelplvix 7/irg. Hartman, 1919 185 x 150 — — Stated | |||
Armadillo Newman, 1917. —-— —— 53 Calculated | |||
Mouse Sobotta, 1895 —— — 59 Stated | |||
{ 2: :2 : §§Z‘E:2ff2f;.““°°‘ | |||
Gerlaeh, 1906 71 x 55 53 63 x 54 Calculated (few eggs) | |||
Kirkham, 1907 —-— — 71 x 64 Calculated (7. eggs) | |||
Lams and Doormc I907 —- — 68 Osmic fix., stated | |||
’ — — 67. Non-os. fix., stated | |||
Long and Mark, 1911 77 50 59 Cf. Table 1 | |||
Van der Stricht, 197.3 93 x 64 67 x 60 80 x 67. Cf. Table 7. | |||
Kremer, 197.4 75 x 75 65 x 55 70 x 70 Calculated | |||
Rat Kirkham and Burr, 1913 77 x 77. 65 x 55 69 x 63 Calculated | |||
Sobotta and Burckhard, 65 6o — Stated | |||
1910 | |||
Kremer, 197.4 63 x 55 45 x 45 53 x 47 Calculated | |||
Guinea-pig Rein, 1883 —— — 84 From Lams, 1913 | |||
Lams and Doormc I907 —-— -— { 83 Osmic flx., stated | |||
’ — —— 79 Non-osmic fix., stated | |||
was 91 2:8 75 §:::::;d.f:;:,fg“°" | |||
Lams I913 __ _ { 80 fleming flx.; calculated | |||
’ 70 N on-osmic fix.; calcu. lated | |||
0. Van der Stricht, 197.3 87 x 60 67 x 60 77 x 63 Cf. Table 7. | |||
Dog 0. Van der Stricht, 197.3 17.3 x 87 95 x 80 111 x 97. Cf. Table 7. | |||
Cat R. Van der Stricht, 1911 180 x 98 111 x 90 ~ 7. eggs; calc. | |||
Longley, 1911 97. 79 x 74 — Calculated | |||
0. Van der Stricht, 197.3 100 x 90 87 x 81 95 x 84 Calculated | |||
Ferret Robinson, 1918 133 x 116 98 110 Calculated | |||
Horse Hartman —— — 135 Carnegie collection (in | |||
toto prep.) | |||
Bat Van Beneden and Julin, 113 90 104 Calculated | |||
1880 | |||
0. Van der Stricht, 1969 110 x 105 50 x 44 95 x 78 Many eggs; calculated | |||
0. Van der Stricht, 197.3 97 x 7o 81 x 67 90 x 68 3 eggs; calculated | |||
Human Nagel, 1888 199 x 194 170 x 165 — 7. eggs (with zona) | |||
Waldeyer -— — 130 1 egg | |||
Bumm (Gynecology) —— — 7.00 Stated (with zona) | |||
Késllikcr (Grundriss) —-— — 7.oo Stated (with zona) | |||
0. Van der Stricht, 1905 157 17.0 x 110 140 x 17.1 Calculated from 13 figs. | |||
0. Van der Stricht, 197.3 179 x 103 107 x 97. 141 x 103 Calculated 4 eggs | |||
Hartman —-— — 17.0 x 110 1 egg (Carnegie) | |||
Monkey | |||
(M. mmutrinus) Selenka, 1903 —— — Ca. 40 Stated | |||
(M. rbmu) Hartman 108 x 100 105 x 90 110 x 93 Carnegie Coll. | |||
Gibbon Hartman —-— 87 x 80 — 1 egg (Carnegie Coll.) | |||
Gorilla Hartman —— — 90 x 87 1 egg (Carnegie C011.) | |||
378 | |||
TABLE 5 | |||
Tubal am medied in section: after fixation, either in tine ar after firxt being remwed from the tube. .1‘ tarred* in the latter | |||
case. Size in micro (vitellu: or true ovum only) | |||
ANIMAL AUTHORITY mxunm mnmuu AVERAGE nmmgxs | |||
Didelphis (opossum) *Hill, 1918 (D. aurita) 170 x 150 117. x 100 17.6 x 117 Cleavage; calculated | |||
*Hartman, 1919 (D. 1/irg.) 148 x 17.5 107. x 76 17.7. x 104 Stated | |||
Hedgehog *fischer, A. 46 x 40 —— — One 3-celled egg; calculated | |||
Baumeister, I913 —— —— 69 x 54 One egg; calculated | |||
Mole Heape, 1886 159 C?) 17.0 17.5 Calculated | |||
Mouse Sobotta, 1895, 1898 — — 59 to 60 Stated | |||
— —— 6 O ' . Lams and Dootmc’ 190 7 { — 5: Nztlifislildcid 1sit:.t;c;lI:ated | |||
Gerlach, 1906 68 x 55 48 x 41 60 x 48 Many eggs | |||
Anikiew, 1908 60 x 58 — — Calculated | |||
Long and Mark, 1911 —— — 55 Cf. Table 1 | |||
Kat Sobotta and Burckhard, 60 55 — Stated and calculated | |||
1910 | |||
Kirkham and Burt, 1913 67 x 63 55 x 53 61 x 57 Calculated | |||
Huber, 1915 70 x 67. Few eggs | |||
. O . ._ | |||
Guinea-pig Lams and Doormc, 1907 { N:)1:11:sf!'1n:cic, stand | |||
90 x 74 77. x 58 87. x 67 Cale. from figures X | |||
Rubaschkin, 1905 530 | |||
60 55 — Stated | |||
Lams, 1913 60 45 55 Calculated | |||
Rabbit *Assheton, 1894 145 130 133 Cale. 7 figs. X 165 | |||
*Nihoul, 197.6 96 x 97. 86 x 8o 91 x 83 Calc. Benda fix. | |||
Dog *0. Van der Stricht, 197.3 117 x 103 83 x 70 107. x 87 Calculated; cf. Table 7. | |||
Cat R. Van der Stticht, 1911 114 x 100 89 x 75 105 x 93 Calculated | |||
Bonnet, 1897 — -— 100 1 egg ca1c.; fleming fix. | |||
Bonnet (text), 197.7. — —— 111 x 106 1 egg calc. | |||
*Longley, 1911 — — 99 x 81 Calculated | |||
Hill and Tribe, 197.4 90 x 80 69 x 57 87. x 7o Stated | |||
Sheep *Assheton, 1898 17.3 105 114 Calculated | |||
Pig *Assheton, 1898 116 81 100 x 95 Calculated | |||
Deer Keibel, 1901 115 111 x 106 113 x 108 Calculated | |||
Bat Van det Stricht, 1909 83 x 73 60 70 x 65 "Selected as typical" | |||
Van det Stricht, 197.3 97 x 70 54 x 53 73 x 67. Cf. Table 7. | |||
Hartman 87 x 73 Carnegie Coll.; 1 egg | |||
Tatsius Hubrecht, 1907. 82. x 70 77. 77 x 71 Calculated | |||
Monkey (M. neme:- Selenka, 1903 — — 40 4-celled | |||
trimet) | |||
that measurements based on even the best | |||
fixed material, especially th-at fixed in | |||
situ, fall short of the actual size of the | |||
living egg. This is entirely aside from the | |||
irregular shapes which the eggs assume | |||
when fixed in situ. I have seldom seen a | |||
nicely rounded egg fixed and prepared in | |||
the fallopian tube of any animal and I | |||
presume that Sobotta had the same experience. Nevertheless this author, by | |||
“artistic license," pictures his specimens large collection of opossum eggs at the | |||
University of Texas. Many batches of | |||
eggs and embryos were at that time photographed in physiological salt solution | |||
immediately after removal from the | |||
animal. With the assistance of Dr. | |||
Heuser, at the Carnegie Laboratory of | |||
Embryology, many remarkable photographs of the living rabbit egg in cleavage | |||
and germ-layer formation have been secured by Dr. P. W. Gregory and others, | |||
TABLE 6 | |||
Size: of egg: removed from ovary and meamred in living state. Size: in micm. Vitellu: (Sea alm Table 3) | |||
ANIMAL AUTHORITY MAXIMUM MINIMUM AVERAGE REMARKS | |||
Ornithorhynchus Gatenby and Hill, 192.4 4.4 x 4.16 — — 4400 micra | |||
mm. | |||
Ornithorhynchus Caldwell, 1887 2.5 mm. —- — 2.5oo micra | |||
Echidna Caldwell, 1887 3 .o mm. — — 3ooo micra | |||
Mouse Kirkham, 1907 — — 8o | |||
Guinea-pig Bischoff, 1852. — — 75 Calc. from figs. X 350 | |||
Reichert, 1861 —- — 87 Calc. from figs. X 32.0 | |||
Rein, 18_83 — — 65 Calc. from 1 fig. | |||
Rabbit Bischoff, 1842. 182. 142. 161 Stated (1 P.Z. = 2.5 mm.) | |||
Dog Bischoif, 1845 190 166 — Stated | |||
Bischoff, 1844 166 160 — Stated (from polyov. foll.) | |||
Cat Krause, 1838 170 no 144 Six eggs; calculated | |||
Longley, 1911 130 105 — Stated | |||
Goat Krause, 1838 185 17.0 — 3 eggs; calculated | |||
Pig Bischoff, 1844 140 111 — Several eggs | |||
Lowery, 1911 157 — — "Largest of many" | |||
Bat Van Beneden and Julin, 1880 — — 105 1 egg | |||
Macaque Krause, 1838 140 92. 118 3 eggs | |||
in what he considered their normal | |||
rounded shape. His drawings are the | |||
illustrations of maturation, fertilization | |||
and cleavage of the mammalian egg most | |||
used in the embryological textbooks of | |||
all countries. | |||
THE STUDY OF THE LIVING EGG | |||
What were perhaps the beginnings of a | |||
new method in the study of the mammalian egg were made in 1918 by Dr. C. H. | |||
Heuser, who, with the writer, under the | |||
auspices of the Wistar Institute, made a and negatives of the early stages of living | |||
eggs of other mammals are rapidly accumulating. Indeed, at this laboratory Dr. | |||
W. H. Lewis is doing pioneer work in the | |||
cinematography of the developing rabbit | |||
egg, as he is combining tissue culture with | |||
motion picture technique. He has thus | |||
far succeeded in keeping the egg alive in | |||
rabbit blood plasma for over a week | |||
and photographing its normal development for over four days—that is, through | |||
cleavage and the formation of the seg | |||
mentation cavity. The observer may see the entire process before his eyes in a few | |||
minutes and much may be learned which | |||
would absolutely escape notice by other | |||
methods. | |||
taken in Texas and of the rabbit egg after | |||
photographs taken by Dr. Gregory and | |||
Dr. Lewis. | |||
This section on the measurement of the | |||
TABLE 7 | |||
Tubal um mulled in the living state. Size: in micra. Meamrement: of ovum proper or vitellu: only, or in a few carer, | |||
chiefly early cleavage rtagee, inner diameter of game. | |||
See who Table 3 | |||
ANIMAL AUTHORITY MAXIMUM mmnnm AVERAGE REMARKS | |||
Platypus Burrell, 197.7 3.0 mm. — — Whole egg 17 x 14 mm. | |||
Echidna Simon, 1894 — —— —- Whole egg 16 x 13 mm. | |||
Dasyurus Hill, 1911 300 x 7.90 —— 7.50 x 7.40 Stated | |||
Opossum Hartman, 1919 157 x 157. 108 x 100 130 x 17.3 Stated | |||
Hedgehog Keibel, 1888 17.0 — no (In toto in OsO4); stated | |||
Mouse Kirkham, 1907 78 73 — Stated | |||
Rat Bischoff, 1844 — -—— 100 One egg; stated | |||
Kirkham and Burr, 1913 — — 79 Stated | |||
Guinea-pig Bischofl’, 1857. 106 91 — Stated (3 P.Z. = 80 mm.) | |||
Bischoff, 1857. 74 70 77. Calc. from figs. X 350 | |||
Bischolf, 1857. — — 75 After Lams | |||
Reichert, 1861 — —- 87 After Lams | |||
Hensen, 1876 87. 65 75 Calc. from sev. eggs | |||
Rabbit Bischoff, 1847. 180 139 160 Stated. | |||
Costl, 1834-1849 — — 17.0 Calculated | |||
Hensen, 1876 -— — 1o3 x 93 Calc., 1 fig. | |||
Gréwsdew, 1896 144 17.0 133 Calc., sev. figs. | |||
Dog v. Baer, 187.7 — — 144 "1/15 of a line" | |||
Bischoff, 1845 174 17.5 145 "3 P.Z. = 80 mm." | |||
Hartman — — 17.0 Carnegie Coll. | |||
Cat Longley, 1911 Cf. Table 3 | |||
Hill and Tribe, 197.4 153 x 136 119 x 110 130 x 119 6 eggs in osmic fix. | |||
Sheep Bischoff, 1844 —~ -—— 140 1 egg; stated | |||
Deer Bischoff, 1854 115 Stated | |||
Pig Corner and Amsbaugh,1917 145 135 140 14 eggs, 3 litters | |||
Heuser and Streeter, 197.8 131 116 17.1 10 eggs, 3 litters | |||
Bats Cspp.) Van Beneden, 1911 95 86 91 7. eggs (118, 108 with | |||
zona) | |||
Monkey Corner, 197.3 86 83 — 7. eggs, degenerating | |||
Allen, 197.7 104 87 —-— 7. eggs, degen. | |||
Allen, 192.8 104 1 egg, degen. | |||
Hartman - — 107 1 egg, degen. | |||
Human Allen, et al., 197.8 184 117 137. With zona | |||
Photography thus applied to embryology may therefore be expected to yield | |||
valuable results. Certainly, from negatives the size of the eggs may be calculated at one’s leisure. In Table 3 I have | |||
given a number of measurements, chiefly | |||
of the opossum egg after photographs | |||
living egg must not be closed without | |||
mention of an event of the greatest significance; namely, the discovery of the | |||
first human tubal ovum by Edgar Allen | |||
and associated surgeons (Dr. Pratt of | |||
Detroit and Drs. Newell and Bland of St. | |||
Louis). Seven eggs were recovered from | |||
TABLE 8 | |||
Interpretive table, giving tbe reviewer’: estimate of tbe true | |||
average size of tbe egg of various species of mammal thus | |||
far studied. Studies on tbe living egg are considered | |||
tbe more authoritative and due correction is made for | |||
data based on fixed eggs. Dimension of vitellus only. | |||
fen/einson (1915) probably give: size of entire egg | |||
MOST | |||
mm .::::;B;:. ”3«‘>‘»‘?’s"‘ | |||
IN uxcxm TABLE | |||
Monotrcmata | |||
Platypus . . . . . . . . . . . . . . . . . . . 1.5 mm. | |||
Echidna . . . . . . . . . . . . . . . . . . . 3 .0 mm. | |||
Marsupialia | |||
Dasyurus . . . . . . . . . . . . . . . . . . 2.40 2.80 | |||
Didelphis . . . . . . . . . . . . . . . . . . 140-160 130 | |||
Edentata | |||
Armadillo . . . . . . . . . . . . . . . . . 80 | |||
Cetacea | |||
Whales . . . . . . . . . . . . . . . . . . . . 140 | |||
Insectivora | |||
Mole (Talpa) . . . . . . . . . . . . . . 12.5 90 | |||
Hedgehog (Erinaceus) . . . . . . 100 60 | |||
Rodentia | |||
Mouse . . . . . . . . . . . . . . . . . . . . 70-75 60 | |||
Rat . . . . . . . . . . . . . . . . . . . . . . . 70-75 | |||
Guinea pig . . . . . . . . . . . . . . . . 75-85 80 | |||
Lagomorpha | |||
Rabbit . . . . . . . . . . . . . . . . . . . . 120-130 150 | |||
Carnivora | |||
Dog . . . . . . . . . . . . . . . . . . . . . . . 135-145 180 | |||
Cat . . . . . . . . . . . . . . . . . . . . . . . 17.0-130 | |||
Ferret . . . . . . . . . . . . . . . . . . . . . 17.0 | |||
Ungulata | |||
Horse . . . . . . . . . . . . . . . . . . . . . 13; | |||
Sheep . . . . . . . . . . . . . . . . . . . . . 17.0 130 | |||
Goat . . , . . . . . . . . . . . . . . . . . . . 140 | |||
fig . . . . . . . . . . . . . . . . . . . . . . . 17.0-14o | |||
Cheiroptera | |||
Bat . . . . . . . . . . . . . . . . . . . . . . . 95-105 | |||
Lemurs | |||
Tarsius . . . . . . . . . . . . . . . . . . . . 90 | |||
Primates | |||
Gibbon . . . . . . . . . . . . . . . . . . . . 1 10-110 | |||
M. rbesus . . . . . . . . . . . . . . . . . . 110-17.0 | |||
Gorilla . . . . . . . . . . . . . . . . . . . . 130-140 | |||
Man . . . . . . . . . . . . . . . . . . . . . . 130-140 | |||
six women. The measurements were | |||
made on the fresh eggs and are given in | |||
Table 7. Previously Corner (197.3) and | |||
Allen (197.7) had recovered eggs from the monkey. These were also measured before fixation (Table 7). The egg of | |||
Macacus nemestrinns, in the four-celled | |||
stage, was studied by Selenka (1903) | |||
in the fixed tube and measured in the | |||
shrunken state only 40 micra. These | |||
cases mark the beginning of the study‘ of | |||
the earliest tubal ova in Primates. | |||
THE SIZE OF THE MAMMALIAN EGG | |||
We now return to the original question, | |||
How large is the mammalian egg? The | |||
reflections set down in this review force | |||
the conclusion that for no species of | |||
mammal is there agreement on measurements of the egg. Those reported have a | |||
range far in excess of variations in the | |||
normal living egg, great as these variations undoubtedly are. Perhaps the smallest and the largest of a given species, that | |||
is, the extremes in size range of living eggs, | |||
are not viable. But We know nothing | |||
about this problem; it is one that only | |||
tissue—culture methods can solve. The | |||
reviewer has therefore thought it desirable | |||
to bring together the data contained in | |||
the World's literature (at least in that | |||
major portion available to him) on the | |||
size of the mammalian egg and to present | |||
it for what it is worth. If the figures are | |||
unsatisfactory the study will serve to emphasize the need of further work and more | |||
careful methods than those employed in | |||
respect to the making of measurements in | |||
the past. For the convenience of the | |||
reader the data have been condensed into | |||
Tables 4, 5, 6 and 7, classified according | |||
to the headings of the tables. As a summary of the whole the writer has been | |||
bold enough tentatively to put down in | |||
Table 8 his own ideas as to the normal | |||
range of the average or modal egg size | |||
for the various species of mammals. The | |||
table is based first on the best measurements of the living egg and second on an | |||
evaluation of the data given by the various | |||
authors, due correction being made for | |||
the methods used. The table should, | |||
however, be regarded merely as a basis for | |||
revision in the future. Nevertheless, a | |||
perusal of the figures will show that Van | |||
der Stricht was probably right when he | |||
stated the human egg to be the largest, | |||
that of Muridae the smallest among the | |||
mammiferous animals. It is also apparent | |||
that the smallest eggs are probably not as | |||
small as the former estimates would have | |||
them, the largest not as large as previously | |||
stated. The mouse egg is nearer 7o than | |||
50 micra, the human egg nearer 150 than | |||
zoo. In other Words the table has a tendency to level up the differences in the | |||
sizes of mammalian eggs. | |||
finally it is hoped that the appended | |||
literature list will prove helpful to those | |||
studying the mammalian ovum for thc | |||
first time. Studies on the ovum just | |||
before and just after its discharge from the | |||
ovary Were, of course, considered the | |||
essential studies. Others might have been | |||
added which give sizes of the ovarian egg | |||
incidental to histological studies on the | |||
ovaries; but it is believed that the list | |||
includes a sufficient number of these. The | |||
list of papers and books on tubal ova, | |||
practically all of which have been consulted by the writer, is believed to be | |||
fairly complete. | |||
LIST OF LITERATURE | |||
ALLEN, EDGAR. 1927. The menstrual cycle in the | |||
monkey, Macacus rhesus: Observations on | |||
normal animals, the effects of removal of the | |||
ovaries and the effects of injections of ovarian and | |||
placental extracts into the spayed animals. | |||
Contrib. to Embryol. Vol. 19; Carnegie Inst. of | |||
Wash. Publ. No. 380, pp. 1-44. | |||
197.8. An unfertilized tubal ovum from | |||
Macacus rhesus. Anat. Rec., 37: 351-356. | |||
ALLEN, EDGAR, J. P. Pxxrr, Q. U. Nnwunr. and L. | |||
BLAND. 197.8. Recovery of human ova from | |||
the uterine tubes: time of ovulation in the menstrual cycle. Journ. Am. Med. Assn., 91 (14): | |||
1o18. | |||
Amxnzw, A. 1908. Ueber den Ban des Eiprotoplasma und fiber die excentrische Lagerung der | |||
Kernflguren in einigen Tubeneiern der Hausmaus | |||
(Mus musculus, vat. alba). Anat. Anz., 37.: | |||
320-330. | |||
Assnmox, R. 1894. A re-investigation into the | |||
early stages of the development of the rabbit. | |||
Quart. Journ. Micr. Sci., 37: 113-164. | |||
1898a. The development of the pig during | |||
the first ten days. 15121., 41: 329-359. | |||
1898b. The segmentation of the ovum of | |||
the sheep, with observations on the hypothesis | |||
of a hypoblastic origin for the trophoblast. | |||
16121., 41: 7.o5—~7.67.. | |||
von Bum, KARL ERNST. 187.7. Epistola de ovi | |||
mammalium et hominis genesi. (See also B. | |||
Ottow, translation into German, 197.7.) | |||
BALLOWITZ, E. 1906. Zur Kenntnis der Eifurchung | |||
bei den Insectivoren. Anat. Anz., 7.9: 674. | |||
(Prelim. paper; see Baumeister and Kunsenmiiller.) | |||
BARRY, M. 1838. Researches in embryology, first | |||
series, Phil. Trans. (Ovarian follicles and | |||
eggs.) | |||
1839. Researches in embryology, second | |||
series. (first description of cleavage of cytoplasm.) Ibidrm. | |||
1840. Researches in embryology, third | |||
series. Ibidam. | |||
1841. Supplementary note to a paper | |||
entitled: Researches in embryology, third series: | |||
A contribution to thephysiology of the cell. | |||
Ihidem, p. 193. | |||
1843. Spermatozoa observed within the | |||
mammiferous ovum. Ibidm, p. 33. (See also | |||
Phil. Mag., 1843, May, p. 415.) | |||
Baummsnzn, TH. 1913. Die Entwicklungsvorgéinge | |||
am Keime des Igels (Erinaceus Europaeus L.) | |||
von seinem Uebertritt in den Uterus bis zur | |||
Ausbildung des Mesoderms. Zeitschr. f. wiss. | |||
Zool., 105: 1-86. | |||
Bwnnxnonn, J. 1888. Ueber die Umkehr der | |||
Keimbliitter bei der Scheermaus (Arvicola | |||
amphibius, Desm.). Arch. f. Anat. u. Physiol., | |||
Anat. Abt., pp. 7.79186. (A 47.-celled stage, | |||
48;», fixed in situ in 50% alcohol.) | |||
Brsc11om=,Tr1. L. W. 1847.. Entwicklungsgeschichte | |||
der Sélugethiete und des Menschen. Leipzig. | |||
B1sc1=1o1=r, T11. L. W. 1844. Beweis von der Begattung | |||
unabhangiger periodischer Reifun g und Loslosung | |||
der Eier der Séiugethiere und des Menschen als die | |||
erste Bedingung ihrer Fortpflanzung. Giessen. | |||
1845. Entwicklungsgeschichte des Hundc | |||
eies. Braunschweig. | |||
1857.. Entwicklungsgeschichte des Kanincheneies. Braunschweig. | |||
1857.. Entwicklungsgeschichte des Meetschweinchens. Giessen. | |||
1854. Entwicklungsgcschichte des Rehes. | |||
Giessen. | |||
1863. Ueber die Rauzeit des Fuchses und | |||
die erste Entwicklung seines Eies. Sitz. | |||
Ber. d. k. bayrischen Akad. zu Mfinchen. | |||
1863. Ueber die Bildung des Séiugethiereies | |||
und seine Stellung in der Zellenlehre. | |||
1877. Historisch-kritische Bemerkungen | |||
zu den neuesten Mittheilungen fiber die erste | |||
Entwicklung der Siiugethiereier. Mfinchen. | |||
BONNET, R. 1884. Beitriige zur Embryologie der | |||
Wiederkiiuer, gewonnen am Schafei. Arch. f. | |||
Anat. u. Physiol., Anat. Abth., pp. 17o-7.30. | |||
(Later stages cont. ibidem, 1889, pp. 1-76.) | |||
1897. Beitrige zur Embryologie des | |||
Hundes. Anat. Hefte, (1. Abt.), 9: 419-517.. | |||
(Continued ibidem, 1901, vol. 16, pp. 231-337..) | |||
1 891 . Grundriss der Entwicklungsgeschichte der Hausthiere. Berlin. | |||
1910. Lehrbuch der Entwicklungsge | |||
schichte. 7.nd. ed. 1917.; 4th ed. 197.0; Berlin. | |||
BRANCA, A. 1910. Caracteres des 7. mitoses de | |||
maturation chez l'homme. C. R. de l'Assoc. | |||
des Anat., p. 5. | |||
BURRELL, HARRY. 197.7. The Platypus: its discovery, zoological position, form and characteristics, habits, life history, etc. Sydney. | |||
CALDWELL, W. H. 1887. The embryology of | |||
Monotremata and Marsupalia Part I. Phil. | |||
Trans. Roy. Soc., 178B: 463-486. (Brief abstract in Nature, March 31, 1887, which was | |||
copied in Amer. Nat. for May, 1887.) | |||
Conmm, G20. W. 197.3. Ovulation and menstruation in Macacus rhesus. Contrib. to Embryol., | |||
Vol. 15, Carnegie Inst. of Wash. Pub. No. 337.. | |||
CORNER, G110. W., and A. E. AMSBAUGH. 1917. | |||
Oestrus and ovulation in swine. Anat. Rec., | |||
17.: 7.87-7.91. | |||
Cos-rn, J. J. M. C. V. 1834. Recherches sur la | |||
génération des mammiferes. Paris. | |||
1841. Histoire de la génération et du | |||
développement. | |||
1847-59. Histoire générale et particuliere | |||
du développement des corps organises. (Text | |||
and atlas dated 1849 consulted.) | |||
THE QUARTERLY REVIEW OF BIOLOGY | |||
CRUIKSHANK, WM. 1797. Experiments in which on | |||
the third day after impregnation the ova of | |||
rabbits were found in the Fallopian tubes; and | |||
in the fourth day after impregnation in the uterus | |||
itself; with the first appearance of the foetus. | |||
Phil. Trans. Roy. Soc., vol. 18, pp. 119-137, | |||
abridged ed. of 1809. (first observation of | |||
tubal ova; author just missed discovering the | |||
history of the egg of the rabbit 30 years later | |||
credited to von Baer.) Transl. in Reil’s Archiv | |||
f. d. Physiologic, Vol. 3, 1799. | |||
VON’ EBNER, V. 19oo. Ueber das Verhalten der | |||
Zona pellucida zum Ei. Anat. Anz., 18: 55-67.. | |||
Fxscmm, A. 1905. Zur Kenntnis der Struktur des | |||
Oolemmas der Salugetiereierzellen. Anat. Hefte, | |||
1. Abt., 7.9: 557-585 (Heft 89). | |||
GASSMANN, 0. 197.3. Das Schicksal des unbefruchteten Eies des Menschen. Diss., Gottingen. | |||
(Rev. in Zentrbl. f. Gyn§ik., 197.5, 49: 393.) | |||
Gxrnunr, J. BRONTE. 197.7.. Some notes on the | |||
gametogenesis of Ornithorhynchus paradoxus. | |||
Quart. Jour. Micr. Sci., 66: 475-500. | |||
GATENBY, J. Bnomfi, and J. P. HILL. 197.4. On an | |||
ovum of Ornithorhynchus exhibiting polar | |||
bodies and polyspermy. Quart. Jour. Micr. | |||
Sci., 68: 7.7.9-2.38. | |||
Gunmen, L. 1890. Beitréige zur Morphologie und | |||
Physiologic des Ovulationsvorganges der Sangetiere. Sitz.-Ber. d. physik-med. Societéit in | |||
Erlangen, Heft 7.7., pp. 43-61. | |||
1906. Ueber die Bildung der Richtungs | |||
ktirper bei Mus musculus. Festschrift f. Rosen | |||
thal, Wiesbaden. | |||
ma GRAAF, R. 1677.. De mulierum organis generationi inservientibus tradatus novus. Lugd. | |||
Batav. | |||
Gxossnn, Ono. 197.7. Friihentwicklung, Eihaut— | |||
bildung und Placentation des Menschen und der | |||
Séiugetiere. Miinchen. | |||
Gxwsmzw, W. S. 1896. VVrsuche fiber die kiinstliche Befruchtung von Kanincheneiern. Arch. | |||
f. Anat. u. Physiol., Anat. Abth, pp. 169-304. | |||
HAACKE, W. 1884. Meine Entdeckung des Eierlegens der Echidna hystrix. Zool. Anz., 7: | |||
647-653 | |||
HEAPE, W. The development of the mole (Talpa | |||
Europea); the ovarian ovum and segmentation | |||
of the ovum. Quart. Journ. Micr. Sci., 7.6: | |||
157-174. (Later stages were described ibidem, | |||
1883, vol. 7.3, pp. 412-457.). | |||
1905. Ovulation and degeneration of ova | |||
in the rabbit. Proc. Roy. Soc., 76 : 7.60. | |||
HARTMAN, CARL G. 1919. Studies in the development of the opossum (Didelphis virginiana L.) | |||
III. Description of new material on maturation, cleavage, and entoderm formation. IV. The | |||
bilaminar blastocyst. Journ. of Morphol., 32.: | |||
1-142.. (See also ibidem, vol. 2.7, pp. 1-83.) | |||
HARTMAN, Cam. G. 192.4. Observations on the | |||
viability of themammalian ovum. Amer. Jour. | |||
Obst. and Gynec. 7: 1-4. (See also Smith, | |||
Septima C.) | |||
HAUSMANN. 1840. Ueber die Zeugung und Entstehung des wahren vveiblichen Eies, etc. Hannover (not accessible.) | |||
Hnxsxm, V. 1876. Beobachtung fiber die Befruchtung und Entwicklung des Kaninchens und | |||
Meerschweinchens. Zeitschr. f. Anat. und | |||
Entwicklgesch., 1: 2.13-2.73 and 351-42.3. (See | |||
also Hensen's Article: “Zeugung" in Hermann's | |||
Handbuch f. Physiologie). | |||
Hnusnn, C. H., and Gnono1:'L. Srnnnrnn. 192.8. | |||
Early stages in the development of the pig from | |||
the period of the initial cell cleavage to the time | |||
of the appearance of limb buds. Vol. 2.o, | |||
Contrib. to Embryol., Publication of the Carnegie | |||
Inst. of Wash. No. 394, pp. 1-30. | |||
HILL, J. P. 1910. The early development of the | |||
Marsupalia with especial reference to the native | |||
cat (Dasyurus viverrinus). Quart. Jour. Micr. | |||
Sci., 56: 1-134. | |||
1918. Some observations on the early | |||
development of Didelphys aurita. Quar. Jour. | |||
Micr. Sci., 63: 91-139. | |||
HILL, J. P., and .MARG. T111311. 192.4. The early | |||
development of the cat (Felis domestica). | |||
Quart. Jour. Micr. Sci., 68: 513-602.. | |||
Ho1.1., M. 1891. Ueber die menschliche Eizelle. | |||
Anat. Anz., 6: 551-556. | |||
1893 . Ueber die Reifung der Eizelle bei den | |||
Siiugetieren. Sitz.-Ber. d. kais. Akad. d. Wiss. | |||
(Math-naturwiss. Klasse), Wien, Abth. III, | |||
101: 2.49-3o9. | |||
Human, G. CARL. 1915. The development of the | |||
albino rat (Mus norvigicus albinus). Journ. of | |||
Morph., 2.6: 2.47-387. | |||
Honruzcnr, A. A. W. 1902.. Furchung und Keimblattbildung bei Tarsius spectrum. Verhandl. | |||
kon. Akad. van Wetenschapen, Amsterdam. | |||
Vol. 8. | |||
. 1912.. Friihe Entwicklungsstadien des I gels | |||
und ihre Bedeutung fiir die Vorgeschichte (Phylogenese) des Amnions. Zoologische J ahrbiicher, | |||
Suppl. XV, Festschr. Spengel, 2.: 739-774. | |||
HYRTL, J. 1878. Lehrbuch der Anatomic des | |||
Menschen. Wien. (Page 776, description of an | |||
alleged human ovum over o.3oo mm. in diam.) | |||
JENKINSON, J. W 19oo. A re-investigation of the | |||
early stages of the development of the mouse. | |||
Quart. Jour. Micr. Sci., 43: 61-82.. | |||
385 | |||
JENKINSON, J. W. 1913. Vertebrate Embryology. | |||
Oxford. (Gives a table of egg sizes.) | |||
JONES, Tnos. WHARTON. 1837. On the first changes | |||
in the ova of Mammifera in consequence of impregnation, and the mode of origin of the | |||
chorion. Phil. Trans. Roy. Soc., 2.: 339-345. | |||
(Varied the mistake of deGraaf by confusing the | |||
liquor folliculi with gelatinous envelope of the | |||
rabbit egg). | |||
1838. On the ova of man and mammiferous | |||
brutes as they exist in the ovaries before im | |||
pregnation and on the discovery in them of a | |||
vesicle. London Med. Gazette. (On the ger | |||
minal vesicle of Purkinje). | |||
1885. On the ova of man and the mammifera before and after fecundation. The | |||
Lancet, 2.: 2.83-2.84; 332.-333. (Priority claim | |||
polemic, chiefly contra Barry; made nice needle | |||
dissections of the ovum for study of zona). | |||
K2A'.pvn1.1, J. 1908. Anatomic und Physiologic des | |||
Ovariums der Wiederkiiuer und Schweine. Diss. | |||
Bern. | |||
1908. Beitrag zur Anatomic und Physiologie der Ovarien der wildlebenden und gezéihmten Wiederkiiuer und Schweine. Handwirtsch. | |||
Jahrb. Schweiz, 2.2.: 53-12.9. | |||
KEIBEL, FR. 1888. Zur Entwicklungsgeschichtc | |||
des Igels. Anat. Anz., 3: 632-637. | |||
V 1891. Ueber die Entwicklung des Schweines. Anat. Anz., 6: 193-198. (Prelim. Account.) | |||
1894. Studien zur Entwicklungsgeschichte | |||
des Schweines (Sus scrofa dom.). Schwalbc's | |||
Morphol. Arbeiten, 3: 1-140. (Continued | |||
ibidm, 1896, 5: 17-168). | |||
1897. Normentafeln zur Entwicklungsges | |||
chichte des Schweines (Sus scrofa dom.). Jena. | |||
1899. Zur Entwicklungsgeschichte des | |||
Rehes. Verh. Anatl Ges., Anat. Anz. Ergiinz. | |||
Heft, 16: 64. | |||
1901. Friihe Entwicklungsstadien des | |||
Rehes und die Gastrulation der Siiuger. Verh. | |||
der anat. Gesellsch., Bonn, Anat. Anz., Erginz. | |||
Heft, 19: 184-191. | |||
1902.. Die Entwicklung des Rehes bis zur | |||
Anlage des Mesoblast. Arch. f. Anat. und | |||
Physiol., Anat. Abth., pp. 2.92.-314. | |||
Kxnxrum, W. B. 1907a. The maturation of the | |||
mouse egg. Biol. Bull., 12.(4): 2.59-2.65. | |||
I9o7b. Maturation of the egg of the white | |||
mouse. Trans. Conn. Acad. of Arts and Sci., | |||
13: 65-87. | |||
K6LL1xnn, ALn1m'r. 1879. Lehrbuch der Entwicklungsgeschichte der Menschen und der hijheren | |||
Thiere. Leipzig. 2.nd. ed. | |||
KOLLIKER, ALBERT. 1884. Grundriss der Entwicklungsgeschichte des Menschen und der héiheren | |||
Thiere. and ed. | |||
K6x.L1K1=.R, Amamz-r and VON Enmm. 1907.. Handbuch der Gewebelehre des Menschen. 6th ed., | |||
vol. 3, pp. 402-404. (Gives 7.7.0 to 37.0}; for | |||
the size of the human egg, zona 7 to 11;»; this is | |||
clearly far too high an estimate.) | |||
KRAUSE, C. 1837. “Ei der S2'iugethicre;" pp. | |||
26-30 of article: Vermischte Beobachtungen und | |||
Bemerkungen. Miil1er's Archiv. pp. 1-36. | |||
(Sec tables.) | |||
KREMER, J. 197.4. Das Verhalten der Vorkerne in | |||
befruchtetem Ei der Ratte und der Maus, mit | |||
besonderer Beriicksichtigung ihrer Nucleolen. | |||
Zeitschr. f. mikr.-anat. Forschung, 1(3): | |||
3S3‘39° | |||
197.4b. Studien zur Oogenese der Sangetiere nach Untersuchungen bei der Ratte und | |||
Maus. Archiv f. mikr. Anat., 107.: 337-358. | |||
(Based on Sobotta's collection of 569 ovarial and | |||
144 tubal eggs of the rat and 1700 ovarial and 67 | |||
tubal eggs of the mouse—-total 7.480 eggs). | |||
KuNs1:NMi'11.L1m, M. 1906. Die Eifurchung des | |||
Igels (Erinaccus europaeus, L.) Zeitschr. f. | |||
wiss. Zool., 85(1): 74-106. | |||
Kvpmuzn, C. 1887.. Das Ei von Arvicola arvalis | |||
und die vermeintliche Umkehr der Keimbliitter | |||
an denselben. Sitz.—Ber. d. k. bayer. Akad. d. | |||
Wiss. zu Miinchen, pp. 67.1-637. (Youngest | |||
egg has thickest zona yet reported—3o;/.). | |||
LAFAIX, M. 1911. Contributions :1 l’étude de la | |||
fécondation chez les Mammiféres. These No. | |||
314, Paris, 61 pp. | |||
LAMS, H. 1906. Demonstrations £1 l'Assoc. Anat., | |||
Bordeaux; C. R. p. 144, | |||
1910. Recherches sur l’oeuf de cobaye | |||
(Cavia cobaya), maturation, fécondation, seg | |||
mentation. C. R. Assoc. Anat. Bruxelles, pp. | |||
119-116. | |||
1913. Etude de l’oeuf de Cobaye aux | |||
premiers stades de Yembryogénese. Arch. de | |||
Biol., 7.8: 7.7.9—37.3. | |||
197.4. L’oeuf de la rate pendant les premieres phases de son développement avant son | |||
arrivée dans l’utérus. C. R. Assoc. Anat., pp. | |||
195’I99 | |||
LAMS, H., and J. Doolmfi. 1908. Nouvelles recherches sur la maturation et la fécondation dc | |||
l'oeuf des Mammiferes. Arch. dc Biol., 23(2): | |||
259-365. (White mouse and guinea pig). | |||
Lnucxurr, R. 1853. Art.: “Zeugung"in Wagner’s | |||
Handbuch der Physiologic, Vol. 4, pp. 707 E. | |||
(P. 876 reference to Latheby’s alleged cases of | |||
tubal ova in man.) | |||
THE QUARTERLY REVIEW OF BIOLOGY | |||
LEVI, G. 1914. Das Verhalten der Chondriosomen | |||
in den friihesten Embryonalstadien der Singetiere. Anat. Anz., 46 : 187-193. (See also | |||
next.) | |||
1915. Il comportamento dei condriosomi | |||
durante i pit‘: precoci periodi dello sviluppo dei | |||
Mammiferi. Arch. f. Zellforschung, 13: | |||
471‘S7-4LONG, J. A. 1917.. The living eggs of rats and mice. | |||
Univ. of Calif. Pub. in Zool., 9: 105-136. (See | |||
also Mark and Long. N 0 data on sizes.) | |||
LONG, J. A., and Manx, E. L. 1911. The maturation of the egg of the mouse. Carnegie Inst. of | |||
Washington Pub. No. 147.. 77. pp. (See also | |||
Contrib. No. 7.16 Zool. Lab. Museum of Comp. | |||
Zool., Harvard). | |||
LONGLEY, W. H. 1911. The maturation of the egg | |||
and ovulation in domestic cat. Amer. Joum. | |||
Anat., 17.: 139-168. | |||
Lowmur, L. G. 1911. Prenatal growth of the pig. | |||
Am. Jour. Anat., 17.: 107-138. | |||
MARK, E. L., and J. A. LONG. 1917.. Studies on | |||
early stages of development in rats and mice. | |||
III. The living eggs of rats and mice, with | |||
description of apparatus for obtaining and | |||
observing them. Contrib. from Zool. Lab. of | |||
Museum of Comp. Zool., Harvard College. | |||
MELISSINOS, K. 1907. Die Entwicklung des Eies der | |||
Manse von den ersten Furchung-Phéinomenen bis | |||
zur Festsetzung der Allantois an der Ectop1acentarplatte. Arch. f. mikr. Anat., 70: 577-618. | |||
(No magnifications stated for drawings; no sizes | |||
given.) | |||
Mmor, C. S. 1889. Segmentation of the ovum, | |||
with special reference to the Mammalia. Am. | |||
Nat., 7.3: 463-481; 753-769. (Very general; no | |||
sizes given.) | |||
Mmo-r, C. S., and E. Tunes. 1905. Normal | |||
plates of the development of the rabbit (Lepus | |||
cuniculus L.). No. 5 of Keibel's Normentafeln | |||
zur Entwicklungsgeschichte der Wirbelthicre. | |||
98 ppNAGEL, W. 1888. Das menschliche Ei. Arch. f. | |||
mikr. Anat., 31: 347.—47.3. (Gives complete | |||
history of subject to date and good bibliography). | |||
NEWMAN, H. H. 1917.. The ovum of the ninebanded armadillo. Growth of the oocytcs, ma | |||
turation and fertilization. Biol. Bull., 7.3: | |||
roo-140. | |||
NIEOUL, J. 197.6. Rechcrches sur l’appareil endo | |||
cellulaire dc Golgi dans les premiers stades du | |||
développement des Mammiferes. La Cellule, | |||
37: 7.1-40. | |||
VAN OORDT, G. J. 197.1. Early developmental | |||
stages of Manis javanica Desm. Verh. kon. | |||
Akad. van Wetensch., Amsterdam, Sec. 7., Part | |||
XXI, No. 3, 107. pp. (A few shrunken cleavage | |||
stages are included.) | |||
Orrow, B. 197.7. Karl Ernst Von Baer's "Ueber die | |||
Bildung des Eies der Salugetiere und des Menschen,” mit einer biographischgeschichtlicher | |||
Einfiihrung in deutscher Sprache. Voss, Leipzig, 197.7. (Anniversary edition commemorating | |||
the centenary of the discovery of the mammalian | |||
egg») | |||
Owmv, R. 1834. On the Ova of Ornithorhynchus | |||
paradoxus. Phil. Trans. Roy. Soc., pp. 555-566. | |||
Also 1835. On the young of the Ornithorhynchus paradoxus. Trans. Zool. Soc. London, 1: | |||
7.7.7.-7.18. | |||
1868. The Anatomy of Vertebrates. Vol. | |||
III, p. 717., quotes egg sizes from Darwin's | |||
Variation of Plant: and Animal: under Domesticatian. I have been unable to verify Owen in this | |||
quotation from later editions of Darwin's work. | |||
Sizes quoted, calculated by myself in micra: | |||
man, 141; dog, 158; rabbit, 170; rat, 17.7; mouse, | |||
111; pig, 17.7; cow, 101; guinea pig, 106. | |||
PAINTER, T. 5. 197.8. Cell size and body size in | |||
rabbits. Jour. Exp. Zool., 50: 441-454. | |||
(Polish rabbit's eggs: 12.0, 17.0, 17.0, 17.6 micraav. 17.1;flemish Giant's eggs; 116, 118, 17.0, 17.0, | |||
17.0, 17.0, I7.6—av. 17.0.) | |||
PATTEN, BRADLEY M. 197.7. The Embryology of | |||
the Pig. Philadelphia. | |||
Ponm. 1912.. Unbefruchtetes Ei. Zentrbl. f. | |||
Gyn£ik., 46: 1490. (Alleged human eggs.) | |||
Rmcnmvr, K.-B. 1861. Beitréige zur Entwicklungsgeschichte des Meerschweinchens. Abhandl. | |||
d. k6n. preuss. Akad. d. Wiss., Berlin. | |||
Rum, G. 1883. Beitréige zur Kenntniss der Reifungserscheinungen und Befruchtungsvorgange am | |||
Salugethierei. Arch. f. mikr. Anat., 2.7.: 7.33-7.70. | |||
ROBINSON, ARTHUR. 1918. The formation, rupture, | |||
and closure of ovarian follicles in ferrets and | |||
ferret-polecat hybrids, and some associated | |||
phenomena. Trans. Roy. Soc. of Edinburgh, 57.: | |||
303-367.. | |||
RUBASCI-IKIN, W. 1905. Ueber die Reifungs- und | |||
Befruchtungsprozesse des Meerschweincheneies. | |||
Anat. Hefte, 19(3): 507-553. | |||
SAKURAI, TSUNEJIRO. 1906. Normentafel zur Entwicklungsgeschichte des Rehes (Cervus capreolus). F. Keibel, ed., Jena, 100 pp. (Based on | |||
Keibel‘s material.) | |||
SALVIN-MOORE, J. E., and F. Tozan. 1908. On the | |||
maturation of the ovum in the guinea pig. Proc. | |||
Roy. Soc., 80B: 7.85-7.87. (Brief note.) | |||
SCHMALZ, R. 1911. “Die Geschlechtsorgane" in | |||
Ellenberger’s Handbuch der vergl. Anat. der | |||
387 | |||
Haustiere. Vol. 7., p. 510. (Quotes sizes of | |||
eggs of cow, pig, and other mammals). | |||
SCEMALZ, R. 197.1. Das Geschlechtslcben der Haussaugetiere. Berlin. | |||
SELENKA, E. 1887. Studien iiber die Entwicklungs | |||
geschichte der Thiere. 4. Heft. Das Opossum. | |||
Wiesbaden. | |||
1903. Studien, etc. Menschenaffen, etc. | |||
5. Zur vergleichenden Keimesgeschichte der | |||
Primaten. pp. 37.9—373. (p. 331: “Eifurchung | |||
des Macacus nemestrinus;" a 4-celled egg.) | |||
SEMON, R. 1894. Zur Entwicklungsgeschichte der | |||
Monotremen. Zool. Forschungsreisen in | |||
Australien und malayischem Archipel. Jena. | |||
Bd. II, Lief. 1. | |||
SMITH, SEPTIMA C. 197.5. Degenerative changes in | |||
the unfertilized uterine eggs of the opossum, | |||
with remarks on the so-called parthenogenesis | |||
in mammals. Am. Jour. Anat., 35(1): 81104. | |||
Sosorm, J. 1893. Mitteilungen iiber die Vorgiinge | |||
bei der Reifung, Befruchtung und erste Furchung | |||
des Eies der Maus. Verh. Anat. Gesell. Gottingen, pp. 111—17.0. | |||
1894. Die Befruchtung des Eies der Maus. | |||
Anat. Anz. 9: 2.2.0-7.2.3 (Prelim. note.) | |||
1895. Die Befruchtung und Furchung des | |||
Eies der Maus. Arch. f. mikr. Anat., 45: 15-97.. | |||
(The classic on this subject.) | |||
1895. Die Reifung und Befruchtung des | |||
Wirbeltiereies. Ergebn. d. Anat. u. Entwick1. | |||
Gesch., 5: 507-561. (Rcview.) See also con | |||
tinuation, 1906, ibidem, 6: 493-593. (173 titles.) | |||
1907. Die Bildung der Richtungskorper | |||
bei der Maus. Anat. Hefte, 35: 493-557.. (Heft | |||
106.) | |||
1908. Ueber die Richtungsteilungen des | |||
Siiugetiereies, speziell fiber die Zahl der Rich | |||
tungskérper. Verhndl. d. phys.-med. Gesellsch. | |||
Wiirzburg, 39: 7.41-7.61. | |||
1901. Die erste Entwicklung des Méiuseeies | |||
nach der Furchung. Anat. Anz., Vol. 19, | |||
Erganzungsheft, pp. 4-11. | |||
197.4. Beitriige zur Furchung des Eies der | |||
Séiugetierc mit besondere Beriicksichtigung der | |||
Frage der Determination der Furchung. I. Die | |||
Furchung des Eies der Maus (Mus musculus). | |||
Zeitschr. f. Anat. u. Entwicl<l., 77.: 94-116. | |||
$030114, J., und G. BURCKHARD. 1911. Reifung | |||
und Befruchtung des Eies der weissen Ratte. | |||
Anat. Hefte, 47.: 433-498. | |||
Span, Gnu F. 1883. Beitrag zur Entwicklungsgeschichte der friiheren Stadien des Meerschweinchens bis zur Vollendung der Keimblase. Archiv | |||
f. Anat. u. Physiol., Anat. Abth., pp. 44-60. | |||
Sprmcmz, W. B. 1884. The eggs of Monotremes. | |||
Nature, 31: 132.. | |||
TAFANI, A. 1889. I primi momenti dello sviluppo | |||
dei mammiferi. Rendiconti d. R. Accad. dei | |||
Lincei (C1. di Sci. mor., stor., e filol.), 5(1): | |||
119-125. (No data on sizes.) | |||
1889. La fécondation et la segmentation | |||
étudiées dans les oeufs des rats. Arch. Italiennes | |||
de Biol., 11: 112.. (Unillustrated general report.) | |||
1889. La fecondazione e la segmentazione | |||
studiate nelle uova dei Topi. Accad. med. | |||
fisic., fiorent. (Not available to the present | |||
writer.) | |||
VAN BENEDEN, E. 1870. Recherches sur la composition et la significance de 1'oeuf. Mém. de | |||
l’Acad. roy. de Belgique, Vol. 34. | |||
1875. La maturation de 1'oeuf, 1aféconda | |||
tion et les premieres phases du développement | |||
embryonaire des Mammiferes d'apres les recherches faites sur la Lapin. Bull. Acad. Roy. des | |||
Sci., des Le-ttres et des Beaux-arts de Belgique, | |||
40: 686. | |||
1880. Recherches sur l'embryologie des | |||
Mammiféres. La formation des feuillets chez | |||
le Lapin. Arch. de Biol., 1: 137-2.2.4. (Con | |||
tains frequently copied figures of the rabbit | |||
vesicle.) | |||
1899. Recherches sur les premiers stades | |||
du développement du Murin (Vespertilio muti | |||
nus). Anat. Anz., 16: 307. | |||
1911. De la segmentation, de la formation | |||
de la cavité blastodermique et de l'embryon | |||
didermique chez le Murin. Arch. de Biol., 2.6: | |||
1-64. (This paper, and the succeeding one on | |||
later stages, printed posthumously by Brachet, | |||
ibidmz, 1912., 2.7: 191-402., is also a fertile source | |||
of illustrations for writers of texts on mammalian | |||
embryology.) | |||
VAN BENEDEN, E., and C11. JuL1N. 1880. Observations sur la maturation, la fécondation et la | |||
segmentation de l'oeuf chez les Cheiropteres. | |||
Arch. de Biol., 1: 551-572.. | |||
VAN DER Snucnr, O. 1904. La structure dc l'oeuf | |||
des Mammiferes. Premiere partie: L'oocyte au | |||
THE QUARTERLY REVIEW OF BIOLOGY | |||
stade de l'accroissement. | |||
1—102.. | |||
VAN DER STRICHT, O. 1905. La structure, etc. | |||
Deuxieme partie. Structure de l'oeuf de la femme. | |||
Bull. de l'Acad. Roy. de Med. de Belgique, | |||
Séance Juin 2.4, 1905, pp. 1-35. | |||
1909. La structure, etc. Troisiéme partie. | |||
L’oocyte a la fin du stade d'accroissement, au | |||
stade de la maturation, au stade de la fécondation | |||
et au début de la segmentation (Chauve-souri, | |||
Vesperugo noctula). Mém. Acad. Roy. de | |||
Belgique, Sér. II, Vol. II, pp. 1-176. | |||
192.3. Etude comparée des ovules des Mammiféres aux ditférentes périodes de l'ovogen<‘:se | |||
d'apres les travaux du Laboratoire d'Histologie | |||
et d'Embryologie de l’Université de Gand. Arch. | |||
de Biol., 33: 129-300. 171 figures. | |||
VAN’ DER S1'1uc11'r, R. 1911. Vitellogenése dans | |||
l'ovule du chatte. Arch. de Biol., 2.6: 365-481. | |||
(Prize essay, Univ. of Gand, 1909.) | |||
WAGNER, Runomnn. 1836. Prodromus historiae | |||
generationis hominis atque animalium. Leipzig. | |||
(3 tables of measurements of invertebrate and | |||
vertebrate eggs, incl.: sheep, 148; rabbit, 148; | |||
cat, 150, 110, 2.2.0; rat, 73; bat, 92. micra.) | |||
WALDEYER, W. Eierstock und Ei. Leipzig. 1870. | |||
“Die Geschlechtszellen" in Hertwig's | |||
Handbuch der vergleichenden und experimentellen Entwicklungslehre der Wirbelthiere. Vol 1, | |||
Part 1, pp. 86-476. (P. 32.3: mammalian egg, | |||
100-2.00 micra; hedgehog and mouse, 60; guinea | |||
pig, 90; dog and rabbit, 180.) | |||
WEBER, M. 1904. Die Saugetiere. Jena. | |||
WEIL, C. 1873. Beitriige zur Kenntniss der Befruchtung und Entwicklung des Kanincheneies. | |||
Stricker's (Wiener) med. J ahrbficher. | |||
WESTER, 192.1. Eierstock und Ei. Befruchtung | |||
und Unfruchtbarkeit bei den Haustieren. | |||
Berlin. | |||
WILSON, J. T., and J. P. HILL. 1907. Observations | |||
on the development of Ornithorhynchus. Phil. | |||
Trans. Roy. Soc., 199B: 31-108. | |||
Zscnoxmz, E. 1900. Die Unfruchtbarkeit des | |||
Rindes, ihre Ursachen und Bekimpfung. Zfirich. | |||
Arch. de Biol., 2.1: |
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Hartman CG. How Large is the Mammalian Egg?: A Review. (1929) Quart. Rev. Biol., 4(3): 373-388.
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This historic 1929 paper by Hartman described the differences in oocyte sizes between different species.
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How Large is the Mammalian Egg? A Review
By Carl G. Hartman
Department of Embryology, Carnegie Institution of Washington, Betltimare, Mn.
If one sketch the outline of a hen's egg so as to fill a page of this Journal as nearly as possible, the egg of the oviparous Australian mammal Ornitiiorbynclnm, drawn to the same scale, would be represented by the natural size of the hen's egg, the entire opossum egg with its albumen, by a cross-section of the lead in a pencil, the human egg by a period in average sized type.
Within the phylum Vertebrate; the differences between the smallest eggs, those of mammals, and the largest is even greater. Thus the eggs of certain “man-eating" sharks (Lamnids) are as much as 2.2.0 mm. in diameter. The egg shell of the now exterminated Apyorni: measured 350 mm. or over a foot in its longest diameter. The ostrich egg is -150 mm. in length and has a capacity of 1.2 liters, or over aquart.
In the evolution of mammals, the
Monotremes (Omitlaorbyncbn: and Ecbidnn)
form an interesting link, for they possess
in their hairy covering and milk secreting
glands the chief distinguishing class characteristics of mammals. Yet they “lay"
large yolk-laden eggs from which the
young emerge after a short incubation
outside the female's body. From the
15-millimeter egg of Ornitborlqynclms and
the 15-millimeter egg of Ecbidnet there is a
sudden drop to the typical mammalian
egg, which measures about one-tenth of a
millimeter. It is true that the marsupial
eggs show some transitional characters, as for example, the large albumen layer,
the shell membrane, and a somewhat
richer supply of yolk, as in Dnsyuru:
(Hill). But throughout the Eat/aeriez, the
mammals above the marsupials, the egg is
very uniform, with not much over a twoto-one variation in size (table 8), which
holds from rat to man, from bat to horse,
from mouse to elephant and whale. The
size of the animal bears no relation to -the
size of the egg.
The comparison between the large yolkladen eggs on the one hand and the human
egg or the eggs of most mammals on the
other is not fair to the latter group, for
these represent only the yolk or "vitellus"
of larger eggs. The total diameter of the
hen's egg, for example, is due largely to
the albumen laid down in the oviduct
around the vitellus. The human egg has
no such envelope, and this is true of all
mammals with the exception of the
marsupials and the Lagomorpha (hares
and rabbits). Thus the egg of our only
marsupial, the opossum, has a thick albumen layer enclosed in a thin shell membrane; the rabbit egg lacks the shell membrane, while all other mammalian eggs
have only a highly transparent limiting
membrane, or “zona pellucida," which
they receive in the ovary before their discharge into the oviduct. The opossum
egg, with its opaque white ovum proper
in the center of a transparent, hardly
visible albumen sphere, looks, in reflected light, much like a grain of sago not quite
cooked through—a hyaline sphere with a
white spherule in the center.
This comparison between the egg of fowl and that of mammals must be controlled in another way. The yolk or vitellus of the hen's egg is so laden with fat and protein pabulum for the developing embryo that the egg nucleus, with its associated tiny mass of protoplasm, which alone will make the chick embryo, becomes all but lost on the surface of the yolk. But that speck of protoplasm corresponds to the entire Eutherian egg. The reduction in size has, of course, been made possible by the parasitic habit assumed by the mammalian fetus through implantation in the maternal tissues.
In order to visualize for himself the
actual size of the mammalian egg, the
reader may follow the suggestion which
the Berlin anatomist Waldeyer was wont
to give his students. Spread out, said he,
a sample of sand on a sheet of paper, brush
off the easily visible grains and pick out
the smallest grain, which it is just possible
to see with the naked eye—that speck is
of the order of magnitude of the mammalian egg.
THE DISCOVERY OF THE MAMMALIAN EGG
In view of the small size of the mammalian egg, it is not at all surprising that it so long escaped detection. It was not until 182.7 that von Baer announced the discovery of the real mammalian and human eggs. From the time of de Graaf (1673) to that of von Baer the large vesicular follicle of the ovary was regarded as the egg. We now know that the ovarian follicles that bear de Graaf’s name do not constitute the egg but contain the egg. The clear, limpid “graafian” follicles in the ovary of the rabbit, before their dehiscence, do greatly resemble eggs of about eight days’ development, but how such large eggs were to pass through the narrow lumen of the oviduct did not, it seems, concern many investigators. I read, however, in Ritchie's interesting book, Contribution; to Assist the Study of Ovarian Physiology and Pathology (1865) that Morgagni, in his Aoloermria Anatomim Omnia (1741) made the following reflections: “How much more likely is the conjecture that they (the ovarian follicles) are glands secreting fluid for the purpose of keeping the ovum safe, and helping it to escape when the proper time arrives." The error referred to above was a costly one and doubtless retarded progress in the study of embryology during the century preceding von Baer. It is interesting to note that Jones (1837) varied the error of deGraaf by confusing the gelatinous envelope of the rabbit egg with the liquor folliculi. However, the century following the “Father of Embryology,” the nineteenth, did not produce a large array of investigators who occupied themselves with the study of the early stages of the mammalian egg. Without a doubt the outstanding figure was Bischoff, who published, in the forties and following decades, his classical studies on the rabbit, the dog, the guinea-pig, and other domestic animals, as also the deer. These studies have stood the test of time; Bischoff's measurements on the living eggs were the most extensive up to a very recent date.
My calculations of Bischoff’s data are uniformly
too high. I have followed Keibel’s equivalent of 3
Prussian Inches (R2,) the equal of 80 mm. This
approximates our equivalent of 2.5 mm. for one inch.
Thus the average given for the dog egg (1845, page 7)
is o.oo68 to o.oo7o P.Z. or 1/13 to 1/12. P.L. or 16 to
19/ I00 mm. These dimensions in Iuicra, according to
my calculations would be: 181 to 186, 170 to 184,
166 to 190. It seems that Bischoff attempted exact’ness only in terms of decimal fractions of the P.Z.
(preussischer Zoll.). Since his measurements run
pretty uniform though high it is probable that the unit of measurement he used was smaller than he
thought by a small fraction.
Sobotta (1895) studied 1459 mouse eggs
in maturation and early cleavage, and
Long and Mark (1911) I000 mouse eggs in
maturation and fertilization. These constitute the most extensive studies of a
single species and on a limited phase of
development, but they do not include a
single measurement on the living egg.
As will be pointed out herein, it is the
living egg alone that affords the true
TABLE I
Frem Long and Marie (1911), rbowing change: in size of tin: mam: egg during maturation and fertilization, bared on egg: fixed in Jim
AVERmm— D‘;;’:_ STAGE BEEéIG0sF BER mom Ovarian: Germinal vesicle . . . . . . . . . . . . . . . . . . 109 65 5 Beginning of first maturation division . . . . . . . . . . . . . . . . . . . . . . . . . . 53 62.5 first maturation division . . . . . . . . . . . 7.11 58.0 Tubal.Second spindle . . . . . . . . . . . . . . . . . . . 507 55 .6
Second maturation division . . . . . . . . . 36 53 .6
Pronuclei . . . . . . . . . . . . . . . . . . . . . . . . . 17.3 54.0
Eggs in oviduct 16% hours . . . . . . . . . 5o 53 .3
Eggs in oviduct 7.9 hours . . . . . . . . . . . 50 56 .5
picture of the egg as a whole and it is only recently that such studies have gotten under Way. This fact does not, however, minimize the fundamental processes in the behavior of the egg which only microscopic preparations can disclose; for stained preparations have taught us about the significant behavior of the chromatin, the chief bearer of hereditary characters.
SHRINKAGE OF THE TUBAL EGG
Can we state in definite figures, then, with reasonable accuracy, the dimensions of the ovum in each species of mammal thus far studied? Before answering this question We must further define it. In the first place, We must specify the stage of development considered, for manifestly, sooner or later, the egg begins to grow. In this discussion We shall limit ourselves to the one-celled or undivided stage, or at least to the stage of early cleavage. These alone approximate the freshly discharged egg. Now there is considerable evidence in the literature that the nuclear changes of first maturation division in the ovary, the second division, and fertilization after ovulation involve also changes in the size of the egg, even entirely aside
TABLE 2.
Size: (in micra) of ovarian and tubal egg: calculated by the prerent writer from tbe atla: of van der Striebt
(1923) amlfram /air ltat paper (1909)
OVARIAN TUBAL
“““‘“‘ aces mas Man . . . . . . . . . . . . . . . . . . . . . . . . . 141)(1I3
Dog . . . . . . . . . . . . . . . . . . . . . . . . .. IIIX97. xo2.)(87
Cat . . . . . . . . . . . . . . . . . . . . . . . . .. 95x84 81 X77.
Guinea pig . . . . . . . . . . . . . . . . . . . 77x63 63x58
Bat (197.3) . . . . . . . . . . . . . . . . . . .. 95 X78 7oX65
Bat (1909) . . . . . . . . . . . . . . . . . . .. 9o><69 66X58
Mouse . . . . . . . . . . . . . . . . . . . . . .. 8oX62. 53x53
from the small mass of cytoplasm and nuclear material extruded with the polar bodies. Long and Mark state that a maximal size of the egg is reached at the end of the so-called period of growth, while the egg nucleus is in the condition of a vesicle. From this time to fertilization there is a progressive slight shrinkage, after which the egg increases in size with its sojourn in the tube. Long and Mark's figures are quoted in Table I because they are unique in the number of eggs measured and the care with which the work was done.
Lams and Doorme (1907) were probably the first to call attention to this phenomenon, which 0. Van der Stricht,
their teacher, believed to be quite general
for mammalian eggs. This author also
believed that the low- point varies in
different mammals, but in view of the
condition of the material on which he
made his measurements We may well
doubt that so nice a point could have been
determined‘ by him. That the ovarian
egg is generally reported to be larger than
the tubal egg there is no doubt, as one
can readily see by a study of the literature.
Sobotta in 1905 set down the mouse egg
at 59 micra for both the ovarian and the
tubal stages, but in a later paper he granted
65 to 70 micra to the ovarian, 60 to the
tubal ovum. From Van der Stricht's
extensive data I have calculated Table 7.,
from the standpoint of the present comparison. This author's paper of 197.3
constitutes a veritable atlas of the early
history of the mammalian egg, based on
the most extensive and varied series in
the world.
A similar excess in size of ovarian over
tubal ova I have reported for the opossum,
where, however, the former were measured
in situ, the latter after being washed
from the tube and studied singly. Other
data in the literature were mostly based
on material fixed and sectioned, usually in
situ. The measurements are thus open to
objection; both ovarian and tubal eggs
should be studied alive in the same
medium. This I have done in the case of
the rabbit. Ovarian eggs removed from
the right ovary, excised surgically seven
hours post coitum, measured on the average 17.7. x 119 micra. Nineteen hours
later two eggs Were taken from the left
fallopian tube; they were in the two-celled’
stage when removed, but divided again
and were four-celled before they could be
photographed. They measured 12.4 X 17.4
micra, a little larger than the ovarian
eggs. Dr. W. H. Lewis killed a rabbit
ten hours post coitum, when some of the eggshad been shed while others were still
retained in the follicles. One ovarian
egg measured 119, the other 133 micra;
the average for tubal ova was 17.4 micra.
The progressive changes in size of the
mammalian egg, therefore, await more
extensive study. This Will be made by
better methods in connection with other
studies on the egg.
SHRINKAGE DUE TO fiXATION
The size changes incident to- the vital activities of the developing egg, as set forth above, become insignificant when compared with the shrinkage caused by fixing agents and the after-treatment used in making microscopic preparations. Hence we must know under what conditions the eggs are measured. Since the introduction, about 1870, of the paraffin method of section cutting, by which an egg one—tenth of a millimeter may readily be cut into ten or more sections of convenient thickness, the tendency to use the method on all occasions has been overdone, for it has been substituted for the older and, for some purposes, better method of studying the object in the living state. Refined technique has often been made an end in itself, rather than an aid. fixing fluids, too, cause a variable amount of shrinkage, those containing osmic acid the least of all. The rate at which the reagents are changed is another important factor. With the most careful treatment the Writer kept the shrinkage down, for the most part, to about 15 per cent; more speed in handling the material would certainly have resulted at times in a 30 per cent shrinkage, which is not unusual in much of the work published on the mammalian egg. The study of the mouse egg might be cited in this connection. Sobotta (1905) gives 59 micra for the average mouse egg fixed in either ovary or tube, but in a later paper states that 65 to 70 micra is nearer the truth for the ovarian egg. Kirkham (1907), basing his measurements on the living egg, gives 80 micra for the ovarian, 73 to 78 for the tubal egg. The writer recently photographed five ovarian eggs of a field mouse (sp. 2‘) and these averaged 95 micra in diameter. It is therefore evident (and on this point there is no disagreement among the little data. The proneness of authors to let the reader make the calculations for himself is illustrated by Van der Stricht's invitation (192.3, page 2.79): “I shall not speak further about the exact dimensions of the eggs [he had not yet given any ‘exact dimensions’]—it is easy to calculate them from the drawings.” This invitation I have. accepted, as did Corner
TABLE 3
Measurment: made from photograph: of mammalian egg: taken in the living state. Negative: on file at the Carnegie Laboratory of Embryology, Baltimore. Diameter of o1/am proper (oitellm) or inner diameter of
zona. Dimem-ion: in miera ANIMAL STAGE "U32: 01' AVERAGE SIZE INVESTIGATOR Rabbit 1-4-celled 6 12.6 Gregory Early cleavage 2.2. 12.4 Lewis Ovarian 1 119 Lewis Ovarian 1 133 Lewis Ovarian 5 12.o Hartman 2.—4—celled 2. 12.4 Hartman Mouse Ovarian 5 95 Hartman Dog 1-celled tubal 3 12.0 Hartman Pig 1-celled tubal 4 111 Heuser and Streetet Cleavage 8 12.1 Heuser and Streeter Opossum 56 1-celled tubal 2. 145 Heuser and Hartman 313 1-celled tubal 2. 12.6 x 1o6 Heuser and Hartman 351 1-celled tubal 11 108 x 1oo Heuser and Hartman 336, 337 Cleavage 6 151 x 140 Heuser and Hartman 842. Early tubal 7 157 x 152. Hartman 833 1-celled tubal 2. 173 Hartman 766 Uterine 1 141 Hartman
Various litters of Uterine 100 155 Hartman opossum
authorities) that the fixed egg is no criterion of normal size of the living, functioning egg.
A further complication is encountered if one attempts to calculate the size of eggs from authors’ illustrations where the magnifications are indicated. Articles that fail to indicate magnifications are, of course, of no avail for the purpose of this study (e.g., Rein, Melissinos). Were we to refrain entirely, however, from making calculations from the illustrations in the literature, there would remain jolly
(CoWdry’s "Special Cytology,” volume
II, page 1112.). The results must, however, fall somewhat short of the true
diameter of even the fixed egg, for sections
are selected that pass through features of
interest, namely the egg nucleus, division
spindle, and polar bodies. If these landmarks happen to fall in the middle section
of the series the section fairly represents
the act ual size of the egg; if, on the other
hand, the section is a tangential one, the
egg is actually larger than the section
shows it to be. It is therefore apparent
TABLE 4
Egg: (vitelle: only, or inner diameter of (ma) meamred in prepared section: affixed ovaries. Size: in micra
ANDIAL AUTHORITY IMAXIMUM MINIMUM AVERAGE REMARKS
Dasyurus Hill, 1911 7.70 x 7.60 7.80 x 17.6 7.40 Stated
Didelpbis aurita Hill, 1918 — — 147. x 17.9 Stated
Didelplvix 7/irg. Hartman, 1919 185 x 150 — — Stated
Armadillo Newman, 1917. —-— —— 53 Calculated
Mouse Sobotta, 1895 —— — 59 Stated
{ 2: :2 : §§Z‘E:2ff2f;.““°°‘
Gerlaeh, 1906 71 x 55 53 63 x 54 Calculated (few eggs) Kirkham, 1907 —-— — 71 x 64 Calculated (7. eggs) Lams and Doormc I907 —- — 68 Osmic fix., stated
’ — — 67. Non-os. fix., stated
Long and Mark, 1911 77 50 59 Cf. Table 1 Van der Stricht, 197.3 93 x 64 67 x 60 80 x 67. Cf. Table 7. Kremer, 197.4 75 x 75 65 x 55 70 x 70 Calculated
Rat Kirkham and Burr, 1913 77 x 77. 65 x 55 69 x 63 Calculated Sobotta and Burckhard, 65 6o — Stated
1910
Kremer, 197.4 63 x 55 45 x 45 53 x 47 Calculated
Guinea-pig Rein, 1883 —— — 84 From Lams, 1913 Lams and Doormc I907 —-— -— { 83 Osmic flx., stated
’ — —— 79 Non-osmic fix., stated
was 91 2:8 75 §:::::;d.f:;:,fg“°"
Lams I913 __ _ { 80 fleming flx.; calculated ’ 70 N on-osmic fix.; calcu. lated
0. Van der Stricht, 197.3 87 x 60 67 x 60 77 x 63 Cf. Table 7.
Dog 0. Van der Stricht, 197.3 17.3 x 87 95 x 80 111 x 97. Cf. Table 7.
Cat R. Van der Stricht, 1911 180 x 98 111 x 90 ~ 7. eggs; calc. Longley, 1911 97. 79 x 74 — Calculated 0. Van der Stricht, 197.3 100 x 90 87 x 81 95 x 84 Calculated
Ferret Robinson, 1918 133 x 116 98 110 Calculated
Horse Hartman —— — 135 Carnegie collection (in
toto prep.) Bat Van Beneden and Julin, 113 90 104 Calculated 1880
0. Van der Stricht, 1969 110 x 105 50 x 44 95 x 78 Many eggs; calculated 0. Van der Stricht, 197.3 97 x 7o 81 x 67 90 x 68 3 eggs; calculated
Human Nagel, 1888 199 x 194 170 x 165 — 7. eggs (with zona) Waldeyer -— — 130 1 egg Bumm (Gynecology) —— — 7.00 Stated (with zona) Késllikcr (Grundriss) —-— — 7.oo Stated (with zona) 0. Van der Stricht, 1905 157 17.0 x 110 140 x 17.1 Calculated from 13 figs. 0. Van der Stricht, 197.3 179 x 103 107 x 97. 141 x 103 Calculated 4 eggs Hartman —-— — 17.0 x 110 1 egg (Carnegie)
Monkey
(M. mmutrinus) Selenka, 1903 —— — Ca. 40 Stated (M. rbmu) Hartman 108 x 100 105 x 90 110 x 93 Carnegie Coll. Gibbon Hartman —-— 87 x 80 — 1 egg (Carnegie Coll.) Gorilla Hartman —— — 90 x 87 1 egg (Carnegie C011.) 378
TABLE 5
Tubal am medied in section: after fixation, either in tine ar after firxt being remwed from the tube. .1‘ tarred* in the latter
case. Size in micro (vitellu: or true ovum only)
ANIMAL AUTHORITY mxunm mnmuu AVERAGE nmmgxs Didelphis (opossum) *Hill, 1918 (D. aurita) 170 x 150 117. x 100 17.6 x 117 Cleavage; calculated
- Hartman, 1919 (D. 1/irg.) 148 x 17.5 107. x 76 17.7. x 104 Stated
Hedgehog *fischer, A. 46 x 40 —— — One 3-celled egg; calculated Baumeister, I913 —— —— 69 x 54 One egg; calculated Mole Heape, 1886 159 C?) 17.0 17.5 Calculated Mouse Sobotta, 1895, 1898 — — 59 to 60 Stated — —— 6 O ' . Lams and Dootmc’ 190 7 { — 5: Nztlifislildcid 1sit:.t;c;lI:ated Gerlach, 1906 68 x 55 48 x 41 60 x 48 Many eggs Anikiew, 1908 60 x 58 — — Calculated Long and Mark, 1911 —— — 55 Cf. Table 1 Kat Sobotta and Burckhard, 60 55 — Stated and calculated 1910 Kirkham and Burt, 1913 67 x 63 55 x 53 61 x 57 Calculated Huber, 1915 70 x 67. Few eggs . O . ._ Guinea-pig Lams and Doormc, 1907 { N:)1:11:sf!'1n:cic, stand 90 x 74 77. x 58 87. x 67 Cale. from figures X Rubaschkin, 1905 530 60 55 — Stated Lams, 1913 60 45 55 Calculated Rabbit *Assheton, 1894 145 130 133 Cale. 7 figs. X 165
- Nihoul, 197.6 96 x 97. 86 x 8o 91 x 83 Calc. Benda fix.
Dog *0. Van der Stricht, 197.3 117 x 103 83 x 70 107. x 87 Calculated; cf. Table 7. Cat R. Van der Stticht, 1911 114 x 100 89 x 75 105 x 93 Calculated Bonnet, 1897 — -— 100 1 egg ca1c.; fleming fix. Bonnet (text), 197.7. — —— 111 x 106 1 egg calc.
- Longley, 1911 — — 99 x 81 Calculated
Hill and Tribe, 197.4 90 x 80 69 x 57 87. x 7o Stated Sheep *Assheton, 1898 17.3 105 114 Calculated Pig *Assheton, 1898 116 81 100 x 95 Calculated Deer Keibel, 1901 115 111 x 106 113 x 108 Calculated Bat Van det Stricht, 1909 83 x 73 60 70 x 65 "Selected as typical" Van det Stricht, 197.3 97 x 70 54 x 53 73 x 67. Cf. Table 7. Hartman 87 x 73 Carnegie Coll.; 1 egg Tatsius Hubrecht, 1907. 82. x 70 77. 77 x 71 Calculated Monkey (M. neme:- Selenka, 1903 — — 40 4-celled
trimet)
that measurements based on even the best fixed material, especially th-at fixed in situ, fall short of the actual size of the living egg. This is entirely aside from the irregular shapes which the eggs assume when fixed in situ. I have seldom seen a nicely rounded egg fixed and prepared in the fallopian tube of any animal and I presume that Sobotta had the same experience. Nevertheless this author, by “artistic license," pictures his specimens large collection of opossum eggs at the University of Texas. Many batches of eggs and embryos were at that time photographed in physiological salt solution immediately after removal from the animal. With the assistance of Dr. Heuser, at the Carnegie Laboratory of Embryology, many remarkable photographs of the living rabbit egg in cleavage and germ-layer formation have been secured by Dr. P. W. Gregory and others,
TABLE 6 Size: of egg: removed from ovary and meamred in living state. Size: in micm. Vitellu: (Sea alm Table 3)
ANIMAL AUTHORITY MAXIMUM MINIMUM AVERAGE REMARKS Ornithorhynchus Gatenby and Hill, 192.4 4.4 x 4.16 — — 4400 micra mm. Ornithorhynchus Caldwell, 1887 2.5 mm. —- — 2.5oo micra Echidna Caldwell, 1887 3 .o mm. — — 3ooo micra Mouse Kirkham, 1907 — — 8o Guinea-pig Bischoff, 1852. — — 75 Calc. from figs. X 350 Reichert, 1861 —- — 87 Calc. from figs. X 32.0 Rein, 18_83 — — 65 Calc. from 1 fig. Rabbit Bischoff, 1842. 182. 142. 161 Stated (1 P.Z. = 2.5 mm.) Dog Bischoif, 1845 190 166 — Stated Bischoff, 1844 166 160 — Stated (from polyov. foll.) Cat Krause, 1838 170 no 144 Six eggs; calculated Longley, 1911 130 105 — Stated Goat Krause, 1838 185 17.0 — 3 eggs; calculated Pig Bischoff, 1844 140 111 — Several eggs Lowery, 1911 157 — — "Largest of many" Bat Van Beneden and Julin, 1880 — — 105 1 egg Macaque Krause, 1838 140 92. 118 3 eggs
in what he considered their normal rounded shape. His drawings are the illustrations of maturation, fertilization and cleavage of the mammalian egg most used in the embryological textbooks of all countries.
THE STUDY OF THE LIVING EGG
What were perhaps the beginnings of a new method in the study of the mammalian egg were made in 1918 by Dr. C. H. Heuser, who, with the writer, under the auspices of the Wistar Institute, made a and negatives of the early stages of living eggs of other mammals are rapidly accumulating. Indeed, at this laboratory Dr. W. H. Lewis is doing pioneer work in the cinematography of the developing rabbit egg, as he is combining tissue culture with motion picture technique. He has thus far succeeded in keeping the egg alive in rabbit blood plasma for over a week and photographing its normal development for over four days—that is, through cleavage and the formation of the seg mentation cavity. The observer may see the entire process before his eyes in a few minutes and much may be learned which would absolutely escape notice by other methods.
taken in Texas and of the rabbit egg after photographs taken by Dr. Gregory and Dr. Lewis.
This section on the measurement of the
TABLE 7 Tubal um mulled in the living state. Size: in micra. Meamrement: of ovum proper or vitellu: only, or in a few carer,
chiefly early cleavage rtagee, inner diameter of game.
See who Table 3
ANIMAL AUTHORITY MAXIMUM mmnnm AVERAGE REMARKS Platypus Burrell, 197.7 3.0 mm. — — Whole egg 17 x 14 mm. Echidna Simon, 1894 — —— —- Whole egg 16 x 13 mm. Dasyurus Hill, 1911 300 x 7.90 —— 7.50 x 7.40 Stated Opossum Hartman, 1919 157 x 157. 108 x 100 130 x 17.3 Stated Hedgehog Keibel, 1888 17.0 — no (In toto in OsO4); stated Mouse Kirkham, 1907 78 73 — Stated Rat Bischoff, 1844 — -—— 100 One egg; stated Kirkham and Burr, 1913 — — 79 Stated Guinea-pig Bischofl’, 1857. 106 91 — Stated (3 P.Z. = 80 mm.) Bischoff, 1857. 74 70 77. Calc. from figs. X 350 Bischolf, 1857. — — 75 After Lams Reichert, 1861 — —- 87 After Lams Hensen, 1876 87. 65 75 Calc. from sev. eggs Rabbit Bischoff, 1847. 180 139 160 Stated. Costl, 1834-1849 — — 17.0 Calculated Hensen, 1876 -— — 1o3 x 93 Calc., 1 fig. Gréwsdew, 1896 144 17.0 133 Calc., sev. figs. Dog v. Baer, 187.7 — — 144 "1/15 of a line" Bischoff, 1845 174 17.5 145 "3 P.Z. = 80 mm." Hartman — — 17.0 Carnegie Coll. Cat Longley, 1911 Cf. Table 3 Hill and Tribe, 197.4 153 x 136 119 x 110 130 x 119 6 eggs in osmic fix. Sheep Bischoff, 1844 —~ -—— 140 1 egg; stated Deer Bischoff, 1854 115 Stated Pig Corner and Amsbaugh,1917 145 135 140 14 eggs, 3 litters Heuser and Streeter, 197.8 131 116 17.1 10 eggs, 3 litters Bats Cspp.) Van Beneden, 1911 95 86 91 7. eggs (118, 108 with zona) Monkey Corner, 197.3 86 83 — 7. eggs, degenerating Allen, 197.7 104 87 —-— 7. eggs, degen. Allen, 192.8 104 1 egg, degen. Hartman - — 107 1 egg, degen. Human Allen, et al., 197.8 184 117 137. With zona
Photography thus applied to embryology may therefore be expected to yield valuable results. Certainly, from negatives the size of the eggs may be calculated at one’s leisure. In Table 3 I have given a number of measurements, chiefly of the opossum egg after photographs
living egg must not be closed without mention of an event of the greatest significance; namely, the discovery of the first human tubal ovum by Edgar Allen and associated surgeons (Dr. Pratt of
Detroit and Drs. Newell and Bland of St. Louis). Seven eggs were recovered from
TABLE 8
Interpretive table, giving tbe reviewer’: estimate of tbe true average size of tbe egg of various species of mammal thus far studied. Studies on tbe living egg are considered tbe more authoritative and due correction is made for data based on fixed eggs. Dimension of vitellus only.
fen/einson (1915) probably give: size of entire egg
MOST
mm .::::;B;:. ”3«‘>‘»‘?’s"‘ IN uxcxm TABLE
Monotrcmata
Platypus . . . . . . . . . . . . . . . . . . . 1.5 mm.
Echidna . . . . . . . . . . . . . . . . . . . 3 .0 mm. Marsupialia
Dasyurus . . . . . . . . . . . . . . . . . . 2.40 2.80
Didelphis . . . . . . . . . . . . . . . . . . 140-160 130 Edentata
Armadillo . . . . . . . . . . . . . . . . . 80 Cetacea
Whales . . . . . . . . . . . . . . . . . . . . 140 Insectivora
Mole (Talpa) . . . . . . . . . . . . . . 12.5 90
Hedgehog (Erinaceus) . . . . . . 100 60 Rodentia
Mouse . . . . . . . . . . . . . . . . . . . . 70-75 60
Rat . . . . . . . . . . . . . . . . . . . . . . . 70-75
Guinea pig . . . . . . . . . . . . . . . . 75-85 80 Lagomorpha
Rabbit . . . . . . . . . . . . . . . . . . . . 120-130 150 Carnivora
Dog . . . . . . . . . . . . . . . . . . . . . . . 135-145 180
Cat . . . . . . . . . . . . . . . . . . . . . . . 17.0-130
Ferret . . . . . . . . . . . . . . . . . . . . . 17.0 Ungulata
Horse . . . . . . . . . . . . . . . . . . . . . 13;
Sheep . . . . . . . . . . . . . . . . . . . . . 17.0 130
Goat . . , . . . . . . . . . . . . . . . . . . . 140
fig . . . . . . . . . . . . . . . . . . . . . . . 17.0-14o Cheiroptera
Bat . . . . . . . . . . . . . . . . . . . . . . . 95-105 Lemurs
Tarsius . . . . . . . . . . . . . . . . . . . . 90 Primates
Gibbon . . . . . . . . . . . . . . . . . . . . 1 10-110
M. rbesus . . . . . . . . . . . . . . . . . . 110-17.0
Gorilla . . . . . . . . . . . . . . . . . . . . 130-140
Man . . . . . . . . . . . . . . . . . . . . . . 130-140
six women. The measurements were made on the fresh eggs and are given in Table 7. Previously Corner (197.3) and Allen (197.7) had recovered eggs from the monkey. These were also measured before fixation (Table 7). The egg of Macacus nemestrinns, in the four-celled stage, was studied by Selenka (1903) in the fixed tube and measured in the shrunken state only 40 micra. These cases mark the beginning of the study‘ of the earliest tubal ova in Primates.
THE SIZE OF THE MAMMALIAN EGG
We now return to the original question, How large is the mammalian egg? The reflections set down in this review force the conclusion that for no species of mammal is there agreement on measurements of the egg. Those reported have a range far in excess of variations in the normal living egg, great as these variations undoubtedly are. Perhaps the smallest and the largest of a given species, that is, the extremes in size range of living eggs, are not viable. But We know nothing about this problem; it is one that only tissue—culture methods can solve. The reviewer has therefore thought it desirable to bring together the data contained in the World's literature (at least in that major portion available to him) on the size of the mammalian egg and to present it for what it is worth. If the figures are unsatisfactory the study will serve to emphasize the need of further work and more careful methods than those employed in respect to the making of measurements in the past. For the convenience of the reader the data have been condensed into Tables 4, 5, 6 and 7, classified according to the headings of the tables. As a summary of the whole the writer has been bold enough tentatively to put down in Table 8 his own ideas as to the normal range of the average or modal egg size for the various species of mammals. The table is based first on the best measurements of the living egg and second on an evaluation of the data given by the various authors, due correction being made for the methods used. The table should, however, be regarded merely as a basis for revision in the future. Nevertheless, a perusal of the figures will show that Van der Stricht was probably right when he stated the human egg to be the largest, that of Muridae the smallest among the mammiferous animals. It is also apparent that the smallest eggs are probably not as small as the former estimates would have them, the largest not as large as previously stated. The mouse egg is nearer 7o than 50 micra, the human egg nearer 150 than zoo. In other Words the table has a tendency to level up the differences in the sizes of mammalian eggs.
finally it is hoped that the appended literature list will prove helpful to those studying the mammalian ovum for thc first time. Studies on the ovum just before and just after its discharge from the ovary Were, of course, considered the essential studies. Others might have been added which give sizes of the ovarian egg incidental to histological studies on the ovaries; but it is believed that the list includes a sufficient number of these. The list of papers and books on tubal ova, practically all of which have been consulted by the writer, is believed to be fairly complete.
LIST OF LITERATURE
ALLEN, EDGAR. 1927. The menstrual cycle in the monkey, Macacus rhesus: Observations on normal animals, the effects of removal of the ovaries and the effects of injections of ovarian and placental extracts into the spayed animals. Contrib. to Embryol. Vol. 19; Carnegie Inst. of Wash. Publ. No. 380, pp. 1-44.
197.8. An unfertilized tubal ovum from Macacus rhesus. Anat. Rec., 37: 351-356. ALLEN, EDGAR, J. P. Pxxrr, Q. U. Nnwunr. and L. BLAND. 197.8. Recovery of human ova from the uterine tubes: time of ovulation in the menstrual cycle. Journ. Am. Med. Assn., 91 (14):
1o18.
Amxnzw, A. 1908. Ueber den Ban des Eiprotoplasma und fiber die excentrische Lagerung der Kernflguren in einigen Tubeneiern der Hausmaus (Mus musculus, vat. alba). Anat. Anz., 37.: 320-330.
Assnmox, R. 1894. A re-investigation into the early stages of the development of the rabbit. Quart. Journ. Micr. Sci., 37: 113-164.
1898a. The development of the pig during
the first ten days. 15121., 41: 329-359.
1898b. The segmentation of the ovum of the sheep, with observations on the hypothesis of a hypoblastic origin for the trophoblast. 16121., 41: 7.o5—~7.67..
von Bum, KARL ERNST. 187.7. Epistola de ovi mammalium et hominis genesi. (See also B. Ottow, translation into German, 197.7.)
BALLOWITZ, E. 1906. Zur Kenntnis der Eifurchung bei den Insectivoren. Anat. Anz., 7.9: 674.
(Prelim. paper; see Baumeister and Kunsenmiiller.)
BARRY, M. 1838. Researches in embryology, first series, Phil. Trans. (Ovarian follicles and eggs.)
1839. Researches in embryology, second series. (first description of cleavage of cytoplasm.) Ibidrm.
1840. Researches in embryology, third
series. Ibidam.
1841. Supplementary note to a paper
entitled: Researches in embryology, third series:
A contribution to thephysiology of the cell.
Ihidem, p. 193.
1843. Spermatozoa observed within the mammiferous ovum. Ibidm, p. 33. (See also Phil. Mag., 1843, May, p. 415.)
Baummsnzn, TH. 1913. Die Entwicklungsvorgéinge am Keime des Igels (Erinaceus Europaeus L.) von seinem Uebertritt in den Uterus bis zur Ausbildung des Mesoderms. Zeitschr. f. wiss.
Zool., 105: 1-86. Bwnnxnonn, J. 1888. Ueber die Umkehr der Keimbliitter bei der Scheermaus (Arvicola
amphibius, Desm.). Arch. f. Anat. u. Physiol., Anat. Abt., pp. 7.79186. (A 47.-celled stage, 48;», fixed in situ in 50% alcohol.)
Brsc11om=,Tr1. L. W. 1847.. Entwicklungsgeschichte der Sélugethiete und des Menschen. Leipzig.
B1sc1=1o1=r, T11. L. W. 1844. Beweis von der Begattung
unabhangiger periodischer Reifun g und Loslosung
der Eier der Séiugethiere und des Menschen als die
erste Bedingung ihrer Fortpflanzung. Giessen.
1845. Entwicklungsgeschichte des Hundc eies. Braunschweig.
1857.. Entwicklungsgeschichte des Kanincheneies. Braunschweig.
1857.. Entwicklungsgeschichte des Meetschweinchens. Giessen.
1854. Entwicklungsgcschichte des Rehes. Giessen.
1863. Ueber die Rauzeit des Fuchses und die erste Entwicklung seines Eies. Sitz. Ber. d. k. bayrischen Akad. zu Mfinchen.
1863. Ueber die Bildung des Séiugethiereies
und seine Stellung in der Zellenlehre.
1877. Historisch-kritische Bemerkungen zu den neuesten Mittheilungen fiber die erste Entwicklung der Siiugethiereier. Mfinchen.
BONNET, R. 1884. Beitriige zur Embryologie der Wiederkiiuer, gewonnen am Schafei. Arch. f. Anat. u. Physiol., Anat. Abth., pp. 17o-7.30. (Later stages cont. ibidem, 1889, pp. 1-76.)
1897. Beitrige zur Embryologie des
Hundes. Anat. Hefte, (1. Abt.), 9: 419-517..
(Continued ibidem, 1901, vol. 16, pp. 231-337..)
1 891 . Grundriss der Entwicklungsgeschichte der Hausthiere. Berlin. 1910. Lehrbuch der Entwicklungsge schichte. 7.nd. ed. 1917.; 4th ed. 197.0; Berlin.
BRANCA, A. 1910. Caracteres des 7. mitoses de maturation chez l'homme. C. R. de l'Assoc. des Anat., p. 5.
BURRELL, HARRY. 197.7. The Platypus: its discovery, zoological position, form and characteristics, habits, life history, etc. Sydney.
CALDWELL, W. H. 1887. The embryology of Monotremata and Marsupalia Part I. Phil. Trans. Roy. Soc., 178B: 463-486. (Brief abstract in Nature, March 31, 1887, which was copied in Amer. Nat. for May, 1887.)
Conmm, G20. W. 197.3. Ovulation and menstruation in Macacus rhesus. Contrib. to Embryol., Vol. 15, Carnegie Inst. of Wash. Pub. No. 337..
CORNER, G110. W., and A. E. AMSBAUGH. 1917. Oestrus and ovulation in swine. Anat. Rec., 17.: 7.87-7.91.
Cos-rn, J. J. M. C. V. 1834. Recherches sur la génération des mammiferes. Paris.
1841. Histoire de la génération et du
développement.
1847-59. Histoire générale et particuliere
du développement des corps organises. (Text
and atlas dated 1849 consulted.)
THE QUARTERLY REVIEW OF BIOLOGY
CRUIKSHANK, WM. 1797. Experiments in which on the third day after impregnation the ova of rabbits were found in the Fallopian tubes; and in the fourth day after impregnation in the uterus itself; with the first appearance of the foetus. Phil. Trans. Roy. Soc., vol. 18, pp. 119-137, abridged ed. of 1809. (first observation of tubal ova; author just missed discovering the history of the egg of the rabbit 30 years later credited to von Baer.) Transl. in Reil’s Archiv f. d. Physiologic, Vol. 3, 1799.
VON’ EBNER, V. 19oo. Ueber das Verhalten der Zona pellucida zum Ei. Anat. Anz., 18: 55-67..
Fxscmm, A. 1905. Zur Kenntnis der Struktur des Oolemmas der Salugetiereierzellen. Anat. Hefte, 1. Abt., 7.9: 557-585 (Heft 89).
GASSMANN, 0. 197.3. Das Schicksal des unbefruchteten Eies des Menschen. Diss., Gottingen. (Rev. in Zentrbl. f. Gyn§ik., 197.5, 49: 393.)
Gxrnunr, J. BRONTE. 197.7.. Some notes on the gametogenesis of Ornithorhynchus paradoxus. Quart. Jour. Micr. Sci., 66: 475-500.
GATENBY, J. Bnomfi, and J. P. HILL. 197.4. On an ovum of Ornithorhynchus exhibiting polar bodies and polyspermy. Quart. Jour. Micr. Sci., 68: 7.7.9-2.38.
Gunmen, L. 1890. Beitréige zur Morphologie und Physiologic des Ovulationsvorganges der Sangetiere. Sitz.-Ber. d. physik-med. Societéit in Erlangen, Heft 7.7., pp. 43-61.
1906. Ueber die Bildung der Richtungs ktirper bei Mus musculus. Festschrift f. Rosen thal, Wiesbaden.
ma GRAAF, R. 1677.. De mulierum organis generationi inservientibus tradatus novus. Lugd. Batav.
Gxossnn, Ono. 197.7. Friihentwicklung, Eihaut— bildung und Placentation des Menschen und der Séiugetiere. Miinchen.
Gxwsmzw, W. S. 1896. VVrsuche fiber die kiinstliche Befruchtung von Kanincheneiern. Arch. f. Anat. u. Physiol., Anat. Abth, pp. 169-304.
HAACKE, W. 1884. Meine Entdeckung des Eierlegens der Echidna hystrix. Zool. Anz., 7: 647-653 HEAPE, W. The development of the mole (Talpa Europea); the ovarian ovum and segmentation of the ovum. Quart. Journ. Micr. Sci., 7.6: 157-174. (Later stages were described ibidem, 1883, vol. 7.3, pp. 412-457.).
1905. Ovulation and degeneration of ova in the rabbit. Proc. Roy. Soc., 76 : 7.60.
HARTMAN, CARL G. 1919. Studies in the development of the opossum (Didelphis virginiana L.) III. Description of new material on maturation, cleavage, and entoderm formation. IV. The bilaminar blastocyst. Journ. of Morphol., 32.: 1-142.. (See also ibidem, vol. 2.7, pp. 1-83.)
HARTMAN, Cam. G. 192.4. Observations on the viability of themammalian ovum. Amer. Jour. Obst. and Gynec. 7: 1-4. (See also Smith, Septima C.)
HAUSMANN. 1840. Ueber die Zeugung und Entstehung des wahren vveiblichen Eies, etc. Hannover (not accessible.)
Hnxsxm, V. 1876. Beobachtung fiber die Befruchtung und Entwicklung des Kaninchens und Meerschweinchens. Zeitschr. f. Anat. und Entwicklgesch., 1: 2.13-2.73 and 351-42.3. (See also Hensen's Article: “Zeugung" in Hermann's Handbuch f. Physiologie).
Hnusnn, C. H., and Gnono1:'L. Srnnnrnn. 192.8. Early stages in the development of the pig from the period of the initial cell cleavage to the time of the appearance of limb buds. Vol. 2.o, Contrib. to Embryol., Publication of the Carnegie Inst. of Wash. No. 394, pp. 1-30.
HILL, J. P. 1910. The early development of the Marsupalia with especial reference to the native cat (Dasyurus viverrinus). Quart. Jour. Micr. Sci., 56: 1-134.
1918. Some observations on the early development of Didelphys aurita. Quar. Jour. Micr. Sci., 63: 91-139.
HILL, J. P., and .MARG. T111311. 192.4. The early development of the cat (Felis domestica). Quart. Jour. Micr. Sci., 68: 513-602..
Ho1.1., M. 1891. Ueber die menschliche Eizelle. Anat. Anz., 6: 551-556.
1893 . Ueber die Reifung der Eizelle bei den Siiugetieren. Sitz.-Ber. d. kais. Akad. d. Wiss. (Math-naturwiss. Klasse), Wien, Abth. III, 101: 2.49-3o9.
Human, G. CARL. 1915. The development of the albino rat (Mus norvigicus albinus). Journ. of Morph., 2.6: 2.47-387.
Honruzcnr, A. A. W. 1902.. Furchung und Keimblattbildung bei Tarsius spectrum. Verhandl. kon. Akad. van Wetenschapen, Amsterdam. Vol. 8.
. 1912.. Friihe Entwicklungsstadien des I gels und ihre Bedeutung fiir die Vorgeschichte (Phylogenese) des Amnions. Zoologische J ahrbiicher, Suppl. XV, Festschr. Spengel, 2.: 739-774.
HYRTL, J. 1878. Lehrbuch der Anatomic des Menschen. Wien. (Page 776, description of an alleged human ovum over o.3oo mm. in diam.)
JENKINSON, J. W 19oo. A re-investigation of the early stages of the development of the mouse. Quart. Jour. Micr. Sci., 43: 61-82..
385
JENKINSON, J. W. 1913. Vertebrate Embryology. Oxford. (Gives a table of egg sizes.)
JONES, Tnos. WHARTON. 1837. On the first changes in the ova of Mammifera in consequence of impregnation, and the mode of origin of the chorion. Phil. Trans. Roy. Soc., 2.: 339-345. (Varied the mistake of deGraaf by confusing the liquor folliculi with gelatinous envelope of the rabbit egg).
1838. On the ova of man and mammiferous
brutes as they exist in the ovaries before im pregnation and on the discovery in them of a
vesicle. London Med. Gazette. (On the ger minal vesicle of Purkinje).
1885. On the ova of man and the mammifera before and after fecundation. The Lancet, 2.: 2.83-2.84; 332.-333. (Priority claim polemic, chiefly contra Barry; made nice needle dissections of the ovum for study of zona).
K2A'.pvn1.1, J. 1908. Anatomic und Physiologic des Ovariums der Wiederkiiuer und Schweine. Diss. Bern.
1908. Beitrag zur Anatomic und Physiologie der Ovarien der wildlebenden und gezéihmten Wiederkiiuer und Schweine. Handwirtsch. Jahrb. Schweiz, 2.2.: 53-12.9.
KEIBEL, FR. 1888. Zur Entwicklungsgeschichtc des Igels. Anat. Anz., 3: 632-637.
V 1891. Ueber die Entwicklung des Schweines. Anat. Anz., 6: 193-198. (Prelim. Account.)
1894. Studien zur Entwicklungsgeschichte des Schweines (Sus scrofa dom.). Schwalbc's Morphol. Arbeiten, 3: 1-140. (Continued ibidm, 1896, 5: 17-168).
1897. Normentafeln zur Entwicklungsges chichte des Schweines (Sus scrofa dom.). Jena.
1899. Zur Entwicklungsgeschichte des
Rehes. Verh. Anatl Ges., Anat. Anz. Ergiinz. Heft, 16: 64.
1901. Friihe Entwicklungsstadien des
Rehes und die Gastrulation der Siiuger. Verh.
der anat. Gesellsch., Bonn, Anat. Anz., Erginz. Heft, 19: 184-191.
1902.. Die Entwicklung des Rehes bis zur Anlage des Mesoblast. Arch. f. Anat. und Physiol., Anat. Abth., pp. 2.92.-314.
Kxnxrum, W. B. 1907a. The maturation of the mouse egg. Biol. Bull., 12.(4): 2.59-2.65.
I9o7b. Maturation of the egg of the white mouse. Trans. Conn. Acad. of Arts and Sci., 13: 65-87.
K6LL1xnn, ALn1m'r. 1879. Lehrbuch der Entwicklungsgeschichte der Menschen und der hijheren Thiere. Leipzig. 2.nd. ed.
KOLLIKER, ALBERT. 1884. Grundriss der Entwicklungsgeschichte des Menschen und der héiheren
Thiere. and ed.
K6x.L1K1=.R, Amamz-r and VON Enmm. 1907.. Handbuch der Gewebelehre des Menschen. 6th ed., vol. 3, pp. 402-404. (Gives 7.7.0 to 37.0}; for the size of the human egg, zona 7 to 11;»; this is clearly far too high an estimate.)
KRAUSE, C. 1837. “Ei der S2'iugethicre;" pp. 26-30 of article: Vermischte Beobachtungen und Bemerkungen. Miil1er's Archiv. pp. 1-36. (Sec tables.)
KREMER, J. 197.4. Das Verhalten der Vorkerne in befruchtetem Ei der Ratte und der Maus, mit besonderer Beriicksichtigung ihrer Nucleolen. Zeitschr. f. mikr.-anat. Forschung, 1(3): 3S3‘39° 197.4b. Studien zur Oogenese der Sangetiere nach Untersuchungen bei der Ratte und Maus. Archiv f. mikr. Anat., 107.: 337-358. (Based on Sobotta's collection of 569 ovarial and 144 tubal eggs of the rat and 1700 ovarial and 67 tubal eggs of the mouse—-total 7.480 eggs).
KuNs1:NMi'11.L1m, M. 1906. Die Eifurchung des Igels (Erinaccus europaeus, L.) Zeitschr. f. wiss. Zool., 85(1): 74-106.
Kvpmuzn, C. 1887.. Das Ei von Arvicola arvalis und die vermeintliche Umkehr der Keimbliitter an denselben. Sitz.—Ber. d. k. bayer. Akad. d. Wiss. zu Miinchen, pp. 67.1-637. (Youngest egg has thickest zona yet reported—3o;/.).
LAFAIX, M. 1911. Contributions :1 l’étude de la fécondation chez les Mammiféres. These No. 314, Paris, 61 pp.
LAMS, H. 1906. Demonstrations £1 l'Assoc. Anat., Bordeaux; C. R. p. 144,
1910. Recherches sur l’oeuf de cobaye
(Cavia cobaya), maturation, fécondation, seg mentation. C. R. Assoc. Anat. Bruxelles, pp.
119-116.
1913. Etude de l’oeuf de Cobaye aux
premiers stades de Yembryogénese. Arch. de
Biol., 7.8: 7.7.9—37.3.
197.4. L’oeuf de la rate pendant les premieres phases de son développement avant son arrivée dans l’utérus. C. R. Assoc. Anat., pp. 195’I99 LAMS, H., and J. Doolmfi. 1908. Nouvelles recherches sur la maturation et la fécondation dc l'oeuf des Mammiferes. Arch. dc Biol., 23(2): 259-365. (White mouse and guinea pig).
Lnucxurr, R. 1853. Art.: “Zeugung"in Wagner’s Handbuch der Physiologic, Vol. 4, pp. 707 E. (P. 876 reference to Latheby’s alleged cases of tubal ova in man.)
THE QUARTERLY REVIEW OF BIOLOGY
LEVI, G. 1914. Das Verhalten der Chondriosomen in den friihesten Embryonalstadien der Singetiere. Anat. Anz., 46 : 187-193. (See also next.)
1915. Il comportamento dei condriosomi
durante i pit‘: precoci periodi dello sviluppo dei
Mammiferi. Arch. f. Zellforschung, 13: 471‘S7-4LONG, J. A. 1917.. The living eggs of rats and mice.
Univ. of Calif. Pub. in Zool., 9: 105-136. (See also Mark and Long. N 0 data on sizes.)
LONG, J. A., and Manx, E. L. 1911. The maturation of the egg of the mouse. Carnegie Inst. of Washington Pub. No. 147.. 77. pp. (See also Contrib. No. 7.16 Zool. Lab. Museum of Comp. Zool., Harvard).
LONGLEY, W. H. 1911. The maturation of the egg and ovulation in domestic cat. Amer. Joum. Anat., 17.: 139-168.
Lowmur, L. G. 1911. Prenatal growth of the pig. Am. Jour. Anat., 17.: 107-138.
MARK, E. L., and J. A. LONG. 1917.. Studies on early stages of development in rats and mice. III. The living eggs of rats and mice, with description of apparatus for obtaining and observing them. Contrib. from Zool. Lab. of Museum of Comp. Zool., Harvard College.
MELISSINOS, K. 1907. Die Entwicklung des Eies der Manse von den ersten Furchung-Phéinomenen bis zur Festsetzung der Allantois an der Ectop1acentarplatte. Arch. f. mikr. Anat., 70: 577-618. (No magnifications stated for drawings; no sizes given.)
Mmor, C. S. 1889. Segmentation of the ovum, with special reference to the Mammalia. Am. Nat., 7.3: 463-481; 753-769. (Very general; no sizes given.)
Mmo-r, C. S., and E. Tunes. 1905. Normal plates of the development of the rabbit (Lepus cuniculus L.). No. 5 of Keibel's Normentafeln zur Entwicklungsgeschichte der Wirbelthicre.
98 ppNAGEL, W. 1888. Das menschliche Ei. Arch. f. mikr. Anat., 31: 347.—47.3. (Gives complete
history of subject to date and good bibliography). NEWMAN, H. H. 1917.. The ovum of the ninebanded armadillo. Growth of the oocytcs, ma turation and fertilization. Biol. Bull., 7.3: roo-140. NIEOUL, J. 197.6. Rechcrches sur l’appareil endo cellulaire dc Golgi dans les premiers stades du développement des Mammiferes. La Cellule, 37: 7.1-40.
VAN OORDT, G. J. 197.1. Early developmental stages of Manis javanica Desm. Verh. kon.
Akad. van Wetensch., Amsterdam, Sec. 7., Part
XXI, No. 3, 107. pp. (A few shrunken cleavage
stages are included.)
Orrow, B. 197.7. Karl Ernst Von Baer's "Ueber die Bildung des Eies der Salugetiere und des Menschen,” mit einer biographischgeschichtlicher Einfiihrung in deutscher Sprache. Voss, Leipzig, 197.7. (Anniversary edition commemorating the centenary of the discovery of the mammalian egg»)
Owmv, R. 1834. On the Ova of Ornithorhynchus paradoxus. Phil. Trans. Roy. Soc., pp. 555-566. Also 1835. On the young of the Ornithorhynchus paradoxus. Trans. Zool. Soc. London, 1: 7.7.7.-7.18.
1868. The Anatomy of Vertebrates. Vol. III, p. 717., quotes egg sizes from Darwin's Variation of Plant: and Animal: under Domesticatian. I have been unable to verify Owen in this quotation from later editions of Darwin's work. Sizes quoted, calculated by myself in micra: man, 141; dog, 158; rabbit, 170; rat, 17.7; mouse, 111; pig, 17.7; cow, 101; guinea pig, 106.
PAINTER, T. 5. 197.8. Cell size and body size in rabbits. Jour. Exp. Zool., 50: 441-454. (Polish rabbit's eggs: 12.0, 17.0, 17.0, 17.6 micraav. 17.1;flemish Giant's eggs; 116, 118, 17.0, 17.0, 17.0, 17.0, I7.6—av. 17.0.)
PATTEN, BRADLEY M. 197.7. The Embryology of the Pig. Philadelphia.
Ponm. 1912.. Unbefruchtetes Ei. Zentrbl. f. Gyn£ik., 46: 1490. (Alleged human eggs.) Rmcnmvr, K.-B. 1861. Beitréige zur Entwicklungsgeschichte des Meerschweinchens. Abhandl.
d. k6n. preuss. Akad. d. Wiss., Berlin.
Rum, G. 1883. Beitréige zur Kenntniss der Reifungserscheinungen und Befruchtungsvorgange am Salugethierei. Arch. f. mikr. Anat., 2.7.: 7.33-7.70.
ROBINSON, ARTHUR. 1918. The formation, rupture, and closure of ovarian follicles in ferrets and ferret-polecat hybrids, and some associated phenomena. Trans. Roy. Soc. of Edinburgh, 57.: 303-367..
RUBASCI-IKIN, W. 1905. Ueber die Reifungs- und Befruchtungsprozesse des Meerschweincheneies. Anat. Hefte, 19(3): 507-553.
SAKURAI, TSUNEJIRO. 1906. Normentafel zur Entwicklungsgeschichte des Rehes (Cervus capreolus). F. Keibel, ed., Jena, 100 pp. (Based on Keibel‘s material.)
SALVIN-MOORE, J. E., and F. Tozan. 1908. On the maturation of the ovum in the guinea pig. Proc. Roy. Soc., 80B: 7.85-7.87. (Brief note.)
SCHMALZ, R. 1911. “Die Geschlechtsorgane" in Ellenberger’s Handbuch der vergl. Anat. der
387
Haustiere. Vol. 7., p. 510. (Quotes sizes of eggs of cow, pig, and other mammals).
SCEMALZ, R. 197.1. Das Geschlechtslcben der Haussaugetiere. Berlin. SELENKA, E. 1887. Studien iiber die Entwicklungs geschichte der Thiere. 4. Heft. Das Opossum.
Wiesbaden.
1903. Studien, etc. Menschenaffen, etc. 5. Zur vergleichenden Keimesgeschichte der Primaten. pp. 37.9—373. (p. 331: “Eifurchung des Macacus nemestrinus;" a 4-celled egg.)
SEMON, R. 1894. Zur Entwicklungsgeschichte der Monotremen. Zool. Forschungsreisen in Australien und malayischem Archipel. Jena. Bd. II, Lief. 1.
SMITH, SEPTIMA C. 197.5. Degenerative changes in the unfertilized uterine eggs of the opossum, with remarks on the so-called parthenogenesis in mammals. Am. Jour. Anat., 35(1): 81104.
Sosorm, J. 1893. Mitteilungen iiber die Vorgiinge bei der Reifung, Befruchtung und erste Furchung des Eies der Maus. Verh. Anat. Gesell. Gottingen, pp. 111—17.0.
1894. Die Befruchtung des Eies der Maus.
Anat. Anz. 9: 2.2.0-7.2.3 (Prelim. note.)
1895. Die Befruchtung und Furchung des
Eies der Maus. Arch. f. mikr. Anat., 45: 15-97..
(The classic on this subject.)
1895. Die Reifung und Befruchtung des
Wirbeltiereies. Ergebn. d. Anat. u. Entwick1. Gesch., 5: 507-561. (Rcview.) See also con tinuation, 1906, ibidem, 6: 493-593. (173 titles.)
1907. Die Bildung der Richtungskorper
bei der Maus. Anat. Hefte, 35: 493-557.. (Heft
106.)
1908. Ueber die Richtungsteilungen des
Siiugetiereies, speziell fiber die Zahl der Rich tungskérper. Verhndl. d. phys.-med. Gesellsch.
Wiirzburg, 39: 7.41-7.61.
1901. Die erste Entwicklung des Méiuseeies
nach der Furchung. Anat. Anz., Vol. 19,
Erganzungsheft, pp. 4-11.
197.4. Beitriige zur Furchung des Eies der Séiugetierc mit besondere Beriicksichtigung der Frage der Determination der Furchung. I. Die Furchung des Eies der Maus (Mus musculus). Zeitschr. f. Anat. u. Entwicl<l., 77.: 94-116.
$030114, J., und G. BURCKHARD. 1911. Reifung und Befruchtung des Eies der weissen Ratte. Anat. Hefte, 47.: 433-498.
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