Book - Contributions to Embryology Carnegie Institution No.56-5

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العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt    These external translations are automated and may not be accurate. (More? About Translations)

Mall FP. and Meyer AW. Studies on abortuses: a survey of pathologic ova in the Carnegie Embryological Collection. (1921) Contrib. Embryol., Carnegie Inst. Wash. Publ. 275, 12: 1-364.

In this historic 1921 pathology paper, figures and plates of abnormal embryos are not suitable for young students.

1921 Carnegie Collection - Abnormal: Preface | 1 Collection origin | 2 Care and utilization | 3 Classification | 4 Pathologic analysis | 5 Size | 6 Sex incidence | 7 Localized anomalies | 8 Hydatiform uterine | 9 Hydatiform tubal | Chapter 10 Alleged superfetation | 11 Ovarian Pregnancy | 12 Lysis and resorption | 13 Postmortem intrauterine | 14 Hofbauer cells | 15 Villi | 16 Villous nodules | 17 Syphilitic changes | 18 Aspects | Bibliography | Figures | Contribution No.56 | Contributions Series | Embryology History

Historic Disclaimer - information about historic embryology pages 
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Pages where the terms "Historic Textbook" and "Historic Embryology" appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms and interpretations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

Chapter 5. The Relation of Cyemic to Chorionic Size

The occurrence of hydramnios indicates that in some specimens the relation of cyemic to chorionic size must vary considerably for this reason alone. This could fail to be the case only if hydramnios could be recognized in its beginning, so that such specimens could be excluded. Moreover, since we are as yet unable to recognize the earliest regressive changes in the cyema, this fact too would increase the range of variation in specimens which might be regarded as normal, at present. If we consider specimens classed as pathologic in the Carnegie Collection, the disproportion between cyemic and chorionic size would of course be very much greater. This variation, in fact, is over 800 per cent. Since the cyema may be extremely abortive and evidently also disappear entirely, disproportion between cyemic and chorionic dimensions might be extremely great in these specimens also. But even aside from these considerations, the relation between chorionic and cyemic size can not be constant throughout gestation unless the shape of the conceptus were invariable. But we know that such is not the case, for the greater growth in length of the fetus, placental development, the formation of the chorion lave, and other matters, all tend to change the form of the conceptus. It is true that regression of the villi in the region of the chorion Iseve would be compensated for to some extent by placental formation on the other side of the vesicle, but in such large specimens the extrauterine change in form will be considerable and thus increase the fluctuation in the measurements. However, it is very probable that the closest correlation exists between cyemic and chorionic size, during the early stages of development, when the conceptus probably is still more nearly spherical. During this time the conceptus also undergoes but little change in form during measurement under proper extrauterine conditions; but even at this time the villi always will be a decidedly variable factor in all external measurements of the chorionic vesicle. Hence it would seem that satisfactory results for a comparison of chorionic and cyemic dimensions probably can not be obtained without taking those of the chorionic vesicle regardless of the villi. Such measurements, however, can not be made accurately without bisecting the vesicle.


I do not know whether the increase in amniotic fluid is very constant or not, but if its volume changes disproportionately, even if not independently of the length of the cyema, this fact would introduce another variable and so further obscure the real correlation in size between the cyema and its chorionic vesicle. In addition to all these things, there are, of course, the normal variations in growth and the changes in form effected during parturition and fixation, for very few abortuses are obtained and measured when fresh. Besides, the vesicle and the cyema no doubt vary independently of each other in growth, so that a very broad basis becomes necessary before a reliable comparison between the two can be made. For all these reasons, then, it would seem that the volume, or, better still, the weight, of the empty chorionic vesicle and that of the cyema would be more reliable data for a determination of a correlation between the two.

Embryo. Chorion.
mm.

2 to 4

4 to 10

10 to 15

15 to 20

20 to 25

cm.

less than 1.5

1.5 to 3

2.5 to 4

3.5 to 5

4.0 to 6


Very few data on this matter are available to us in the literature and we must bear in mind that it is not yet possible to distinguish between the early normal and the abnormal. Whether or not the relationship between the dimensions of the cyema and the chorionic vesicle can be used, as suggested by Giacomini (1894), for distinguishing between the normal and abnormal, it is impossible to say at present. But even if such a criterion can not be obtained, a comparison between the size of the cyema and the chorionic vesicle nevertheless may reveal fluctuations in the one or the other, or in both, which might otherwise be overlooked.


Without reference to the excellent older observations of Velpeau (1855), His (1882) concluded that chorionic was related to amniotic size in early specimens, as shown in the accompanying table.


Giacomini stated that embryos with a length of 2 to 4 mm. are contained in vesicles 1.5 cm. long; embryos 4 to 10 mm., in vesicles 1.5 to 3 cm.; embryos 10 to 18 mm., in vesicles 2.5 to 4 cm.; embryos 15 to 20 mm., in vesicles 3.5 to 5 cm. ; and embryos 18 to 20 mm., in vesicles 4 to 6 cm. long. Giacomini also stated, as did His (1882), that the amnions of embryos less than 10 mm. long invest the latter closely and His further stated that the amnion is 1 to 3 mm. distant from embryos 11 to 15 mm. long and that it had fused with the chorion when the embryo had gained a length of 2.5 cm. Schaeffer (1898) stated that embryos 1.15 mm. long are contained in vesicles of 2.5 to 2.7 cm.; embryos 3 mm. long in vesicles of 2.5 cm.; and embryos 8 mm. long in vesicles 7.5 to 8.5 cm. J. Kollmann (1898) gave the relation of chorionic to embryonic size the same as His. Since His and Kollmann give only one chorionic measurement, it is impossible to surmise what their conception of the form of the chorionic vesicle was, but His's table suggests that the relation between embryonic and chorionic length varies from 1-5 to 1-2 by the time the embryo has reached a length of 2 cm.


Eternod (1909 a ) emphasized the fact that the conceptuses described by Reichert, Ahlfeld, and by himself, all were lenticular in form and also flattened somewhat upon one of their faces. The same thing is true of those reported by Bryce and Teacher, Peters, von Spee, and also of some other specimens. Eternod stated that while early conceptuses are lenticular, they later become ovoid, and still later more spherical. According to Eternod, the portion toward the basalis is flattened the most, while that toward the capsularis is more curved.


Since some of the conceptuses called lenticular by Eternod are so very small, their shape scarcely can be attributed to the influence of the surrounding musculature. Hence it would seem that the human conceptus soon loses the inherent sphericity undoubtedly possessed by the ovum. If, as Eternod thought, the villi of early conceptuses are zonal or annular, with two free surfaces which he designated as dorsal and ventral, a further source of variation in the measurements of young specimens would be introduced.


Evans, in an undated circular issued by this laboratory, gave the length of the embryo and the size of the chorionic vesicle as indicated in table 5. Such tabulations as these are very helpful and suggestive and are bound to gain much in value with enlargement of the data upon which they are based. This table from Evans indicates that the conceptus of the third week practically is spherical, that it then rapidly becomes oblong so that its greatest diameter is almost twice that of the second dimension by the fourth week, and that it returns to a more spherical condition in the sixth, seventh, and eighth weeks, during which time its greatest dimension is indicated as only one-sixth longer than the second dimension. Upon comparing the length of the cyema with that of the conceptus as given in table 5, we find that the greatest dimension of the latter is 10 times that of the former in the third week. The greatest dimension of the chorionic vesicle is approximately 6 times that of the embryo in the fourth week; 4.5 times in the fifth week; 3 times in the sixth week; 2.2 times in the seventh; and 1.4 times in the eighth. From this it is seen that there is a rapid and early approximation between the greatest dimension of the chorionic vesicle and the length of the cyema. This might be expected from the fact that growth in length of the cyema is so much greater than growth in the other two dimensions. The irregularities evident in this table probably are attributable to the small series available for the tabulation, to the fact that all measurements of necessity had to be made postpartum, and that they were not made by the same individual.


The exact form of the human conceptus in its early stages still remains unknown, but as indicated by specimens from the literature, it is probably spherical. This sphericity, however, must be lost as soon as the conceptus extends across the uterine cavity or when the cyema reaches a length which brings its cephalic and caudal extremities closer to the chorionic membrane than are the rest of its surfaces. From this time on we might expect the form of the conceptus to become more and more elongated and ovoid. It may be recalled that one of Leopold's specimens of early conceptuses was represented as ovoid or as almost cylindrical even, but one must bear the possibility of molding during abortion and of postpartum distortion in mind. However, it often is difficult to detect elongation attributable to molding during labor, even in conceptuses of considerable size. Conceptuses up to 4 and 5 cm. in greatest dimension usually assume a flattened, ovoid form when placed in fluid of approximately the same specific gravity. One might, I presume, suppose that after the first weeks all conceptuses have a more or less cylindrical form, in consequence of the shape of the uterine or tubal cavities, but the form of early guinea-pig conceptuses throws doubt upon this supposition. They are quite spherical, and the same thing is true of young rabbit conceptuses, even when they have considerably distended the thin-walled cylindrical uterine cornua by reaching a size of one centimeter.


What is needed, however, is a careful series of measurements on selected material, although even such material will not be ideal as long as we remain unable to differentiate early normal from abnormal forms and as long as not all measurements are made either on fresh or on fixed material. Hence it is evident that the field and graph shown in Chart 1, although made upon the basis of selected normal material from the Carnegie Collection, supplemented by data from the literature, probably can not give us anything more than a very rough approximation of a portion of a curve illustrating the relation between cyemic and chorionic size during the first month.


Among the cases used for this graph there are a few in which the cyemic length is somewhat greater than the greatest chorionic measurement. This may be due to the fact that the chorionic vesicle was measured after it was opened and fixed. It is always diffcult to restore the form of opened chorionic sacs in fluid, even with the greatest care, unless they are coated with blood and decidua so that their walls are stiffened.


Chart 1. Field and graph showing correlation between cyemic and chorionic size, based on the 255 selected normal specimens. Uterine specimens indicated by dots, tubal by circles

Mall Meyer1921 chart01.jpg


In some instances conceptuses with different menstrual ages have the same size, a fact which not necessarily finds its explanation in the existence of normal growth differences, but rather in the earlier death of one cyema or conceptus. Other discrepancies between the length of the cyema and the dimensions of the chorionic vesicle may be due to distention of the latter after death of the former, or possibly to actual growth of the chorionic vesicle after the death of the embryo. It is fortunate that we possess a double check on our data, for we can consider the relation of the size of the ovum and the cyema independently, and also can compare each with the menstrual age.


Since the number of conceptuses with embryos of the first month which have been measured is exceedingly small, any curve based on these data necessarily must remain largely conjectural. However, if we regard it as purely tentative, even such a curve nevertheless may be of value. Moreover, its obvious incompleteness will prompt to improvement. As will appear from Chart 1, only 16 cases were available for the construction of the curve for the first month ; 8 of these were from our own collection, 8 from the literature. One of the two embryos, 2.5 mm. long, belongs to a vesicle which is entirely too large and hence falls high on the chart. On consulting the history of the case it was learned that the conceptus was decidedly collapsed and hence very probably distorted. But this is not the only specimen which shows considerable disproportion between the size of the cyema and the conceptus. I do not imply, however, that these disproportions represent wholly normal variations, although until a large series is available for study it will remain impossible to determine the deviation from the average of normal specimens in a given state of development.

The field represented in Chart 1 was plotted from measurements of chorionic vesicles and cyemata below the fourth month, which are listed as normal in the Carnegie Collection. It includes both uterine and tubal specimens; the former are represented by dots and the latter by circles. In addition to these specimens the measurements of 12 young conceptuses from the literature have also been added ; these are represented by crosses. Since scrutiny of the fields made by the use of other than only the greatest dimension of the chorionic vesicle made it evident that the other dimensions were quite useless as criteria, only the greatest measurement was used for the construction of the field as here represented. The greatest dimension of both cyema and chorionic vesicle is represented in millimeters the former on the ordinate and the latter on the abscissa.

Reference to the location on the field of the cases from the literature, and also an inspection of the beginning of the curve, show that the chorionic vesicle forges ahead of the cyema in its growth. This is what one would expect, for embryonic differentiation naturally must be delayed at the start. However, the specimens of conceptuses with a measurement of less than 10 mm. are too few to enable one to regard this part of the curve as more than an approximation of the actual. Between a length of 10 and 20 mm. a considerably larger number of cases are found, and here the curve is more reliable, although considerable scattering of the cases nevertheless is present. To what extent this scattering is due to variations to growth, and to what degree to the fact that the material was perhaps not strictly fresh or normal, it is impossible to say; probably both factors are involved. Moreover, since the chorionic measurements were external, the condition and length of the villi introduce a further factor of fluctuation; for although the average dimensions of normal villi may fluctuate very little in length when large series of conceptuses are concerned, they do vary considerably, not only in different but also in the same specimen. This is especially true when the period of placental differentiation is reached. Hence measurements of the cavity of the chorionic vesicle or those taken from the wall of the bisected vesicle would give far more reliable data, because the variations in thickness of the membranes are slight and one has then to contend only with the question of distention from hydramnios or other causes.


Since the curve is fairly regular throughout, and the disproportion of the cases but slightly greater as the older conceptuses are reached, I think it can be assumed that it is approximately correct in its general relations. With advancing age it is seen that the length of the fetus more and more approximates the greatest dimension of the chorionic vesicle. This is in agreement with common observation and shows that the greatest chorionic dimension no longer can be of any special value for determining the fetal age. Moreover, in older conceptuses the vesicle no longer retains its form.


Since the majority of the tubal specimens fall considerably below the curve, it is evident that development of the fetus was considerably retarded in these specimens. Only a few fall above the curve, but one of these is so very far. above that one is compelled to conclude that the greatest dimension of the chorion was not obtained in this case, or the chorionic vesicle must have been torn and the amniotic fluid drained off. As will be noticed, the length of the fetus in this case exceeds that of the membranes in which it was contained.

From the curve it is seen that the relations apparently existing between the chorionic and cyemic dimensions are approximately those shown in table 6.


Table 5. (From Evans.)

Mall Meyer1921 table05.jpg

Table 6.

Mall Meyer1921 table06.jpg


A comparison of the estimates on the accompanying graph (Chart 1) with the estimates of other investigators previously referred to shows that those of Evans agree most closely with these. However, the present curve can be regarded as provisional only, for it is based upon but 255 cases and upon external measurements alone.



Embryology - 15 Jun 2019    Facebook link Pinterest link Twitter link  Expand to Translate  
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العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt    These external translations are automated and may not be accurate. (More? About Translations)

Mall FP. and Meyer AW. Studies on abortuses: a survey of pathologic ova in the Carnegie Embryological Collection. (1921) Contrib. Embryol., Carnegie Inst. Wash. Publ. 275, 12: 1-364.

In this historic 1921 pathology paper, figures and plates of abnormal embryos are not suitable for young students.

1921 Carnegie Collection - Abnormal: Preface | 1 Collection origin | 2 Care and utilization | 3 Classification | 4 Pathologic analysis | 5 Size | 6 Sex incidence | 7 Localized anomalies | 8 Hydatiform uterine | 9 Hydatiform tubal | Chapter 10 Alleged superfetation | 11 Ovarian Pregnancy | 12 Lysis and resorption | 13 Postmortem intrauterine | 14 Hofbauer cells | 15 Villi | 16 Villous nodules | 17 Syphilitic changes | 18 Aspects | Bibliography | Figures | Contribution No.56 | Contributions Series | Embryology History

Historic Disclaimer - information about historic embryology pages 
Mark Hill.jpg
Pages where the terms "Historic Textbook" and "Historic Embryology" appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms and interpretations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)