Paper - Contributions to the embryology of the marsupialia 4: Difference between revisions
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Introduction | Introduction | ||
[[Paper - Contributions to the embryology of the marsupialia 4-1| | # [[Paper - Contributions to the embryology of the marsupialia 4-1|Critical Review of Previous Observations on the Early Development of Marsupialia]] | ||
# [[Paper - Contributions to the embryology of the marsupialia 4-2|The Ovum of Dasyurus]] | |||
[[Paper - Contributions to the embryology of the marsupialia 4-2| | ## Structure of Ovarian Ovum | ||
## Maturation and Ovulation | |||
## Secondary Egg-membranes | |||
## Uterine Ovum | |||
# [[Paper - Contributions to the embryology of the marsupialia 4-3|Cleavage and Formation of Blastocyst]] | |||
## Cleavage | |||
## Formation of Blastocyst | |||
# [[Paper - Contributions to the embryology of the marsupialia 4-4|Growth of Blastocyst and Differentiation OP THE Embryonal Ectoderm and the Entoderm]] | |||
## Growth of Blastocyst | |||
## Differentiation of the Embryonal Ectoderm and the Entoderm | |||
[[Paper - Contributions to the embryology of the marsupialia 4-3| | ## Establishment of the Definitive Embryonal Area | ||
## Summary | |||
# [[Paper - Contributions to the embryology of the marsupialia 4-5|Chapter V. - Some Early Stages of Perameles and Macropus]] | |||
# [[Paper - Contributions to the embryology of the marsupialia 4-6|Chapter VI. - General Summary and Conclusions]] | |||
# [[Paper - Contributions to the embryology of the marsupialia 4-7|Chapter VII. - The Early Ontogeny of the Mammalia in the Light of the Foregoing Observations]] | |||
## The Early Development of the Prototheria | |||
[[Paper - Contributions to the embryology of the marsupialia 4-4| | ## The Early Development of the Metatheria and Eutheria | ||
## The Entypic Condition of the Eutherian Blastocyst | |||
the Entoderm | |||
[[Paper - Contributions to the embryology of the marsupialia 4-5|Chapter V. - Some Early Stages of Perameles and Macropus]] | |||
[[Paper - Contributions to the embryology of the marsupialia 4-6|Chapter VI. - General Summary and Conclusions]] | |||
[[Paper - Contributions to the embryology of the marsupialia 4-7|Chapter VII. - The Early Ontogeny of the Mammalia in the Light of the Foregoing Observations]] | |||
* Addendum | |||
* List op References | |||
* [[Paper - Contributions to the embryology of the marsupialia 4-Plates|Explanation of Plates]] | |||
==Introduction== | ==Introduction== | ||
:"In mammalian embiyology very many | :"In mammalian embiyology very many surprises are yet in store for us" ([[Embryology History - Ambrosius Hubrecht|Hubrecht]], 08). | ||
The present contribution contains an account of the nrincipal results and conclusions at which I have arrived after a somewhat protracted and much interrupted study of an extensive collection of early developmental stages of Marsupials, ranging from the fertilised egg to the blastocyst in which the two primary germ layers are definitely established. I believe I nm now able to give for the first time an account of early Marsupial ontogeny, based on the examination of an adequate material, and both consistent in itself and with Avhat we know of the early development in the other two Mammalian sub-classes. The material at my disposal was obtained during my tenure of office in the University of Sydney, and with the aid of grants from the Royal Society and of a George Heriot Research Fellowship. It represents the proceeds of some eight years collecting, and comprises a fairly complete series of stages of the native cat (Dasyurus viverrinus), together with a few early stages of other Marsupials, notably Perameles and Macropus. | |||
Dasyurus proved in many ways a convenient subject for embryological purposes. It can readily be trapped in many places in New South Wales; it lives and breeds fairly well in captivity, and though always somewhat intractable, it can, owing to its size, be easily handled, and so may be subjected if necessary to daily exarainationd But it lias this great disadvantage, which it apparently shares with other Marsupials, that a very variable period intervenes between coitus and ovulation. As a consequence, the obtaining of any desired cleavage or early blastocyst stage is largely a matter of chance.^ It is true that the changes which take place in the pouch, in correlation with ovulation and the events connected therewith, do afford in the case of late pregnant females some indication of the stage of development likely to be met with, but these changes are at first of too indefinite a character to be of much service beyond indicating that ovulation may have taken place. | |||
Dasyurus breeds but once a year, the breeding season extending over the winter months - May to August. One remarkable featui'e in the reproduction of Dasyurus, to which I have directed attention in a previous paper (Hill, ’00), may be again referred to here, and that is the fact that there is no correlation between the number of ova shed during ovulation and the accommodation available in the pouch. The normal number of teats present in the latter is six, though the pi-esence of one or two supernumerary teats is not uncommon; the number of ova shed at one period is, as a rule, far in excess of the teat number. I have, for example, several records of the occurrence of from twenty to twenty-five eggs, two of twenty-eight, one of thirty, and one of as many as thirty-five! (twenty-three normal blastocysts and twelve abnormal), there can be little doubt that Dasyurus, like various other Marsupials (e.g. Perameles, Macropus, etc.), has suffered a progressive reduction in the number of young reared, but even making due allowance for that, the excess in production of ova over requii’eraents would still be remarkable enough. Whether this over-production is to be correlated in any way with the occurrence of abnormalities during early development or not, the fact remains that cleavage abnormalities are quite frequently met with in Dasyurus. | |||
that | |||
but | |||
be of | |||
* Perameles, on the other hand, though quite common in many parts of tlie State, is hy no means such a convenient type. It is much less easily trapped than Dasyurus, does not live nearly so well in captivity, and is pai'ticularly difficiilt to handle. I have to thank Mr. D. G. Stead, now of the Department of Fisheries, Sydney, for first directing my attention to the breeding habits of Dasyurus, and also for providing me with the first female from which I obtained segmenting eggs. | |||
of tlie State, is hy no means such a convenient type. It is much less | |||
easily trapped than Dasyurus, does not live nearly so well in captivity, | |||
and is pai'ticularly difficiilt to handle. I have to thank Mr. D. G. Stead, | |||
now of the Department of Fisheries, Sydney, for first directing my | |||
attention to the breeding habits of Dasyurus, and also for providing | |||
me with the first female from which I obtained segmenting eggs. | |||
* For example, I obtained unsegmented ova from the uteri, four, five, six, seven and eight days after coitus, 2-celled eggs six and seven days after, 4-celled eggs eleven and eighteen days after. In one case the young were bom eight days after the last observed act of coitus, in another sixteen days after, and in yet another twenty days after. | |||
six, seven and eight days after coitus, 2-celled eggs six and seven | |||
days after, 4-celled eggs eleven and eighteen days after. In one case | |||
the young were bom eight days after the last observed act of coitus, | |||
in another sixteen days after, and in yet another twenty days after. | |||
===Technique=== | |||
As fixatives, I have employed for ovaries the fluids of Hermann, Flemming, Ohlmacher, and Zenker; for ova and early blastocysts, Hermann, Flemming, Perenyi, and especially picro-nitro-osmic acid (picro-nitric acid [Mayer] 96 C.C., 1 per cent, osmic acid 2 c.c., glac. acetic acid 2 c.c.) ; for later blastocysts, the last-named fluid especiall}'^ also picro-corrosive-acetic aud corrosive-acetic. | |||
To facilitate the handling of ova and early blastocysts during embedding, I found it convenient to attach each specimen separately to a small square of pig’s foetal membrane by means of a dilute solution of photoxylin (1 to 2 per cent.), Orientation of the specimen was then easily effected during final embedding, under the low power of the microscope. The larger blastocysts were double-embedded in photoxylin and paraffin, the cavity of the blastocyst being tensely filled with the photoxylin solution by means of a hypodermic syringe fitted with a fine needle. | |||
in | |||
For the staining of sections, Heidenhain's iron-htematoxylin method proved the most satisfactory, and was almost exclusively employed. Entire portions of the blastocyst wall were stained either with Ehrlich's or Delafield's haematoxylin. | |||
I am much indebted to Mr. L. Scbaeffer, of the Anatomical Department of the University of Sydney, and to Mr. F. Pittock, of the Zoological Department, University College, for invaluable assistance in the preparation of the photomicrographs reproduced on Plates 1 - 5, and also to Mr. A. Cronin, of Sydney, and Miss M. Rhodes, for the drawings from their respective pencils reproduced on Plates 6 aud 7. To Miss V. Sheffield I am indebted for tlie original of fig. 63. | I am much indebted to Mr. L. Scbaeffer, of the Anatomical Department of the University of Sydney, and to Mr. F. Pittock, of the Zoological Department, University College, for invaluable assistance in the preparation of the photomicrographs reproduced on Plates 1 - 5, and also to Mr. A. Cronin, of Sydney, and Miss M. Rhodes, for the drawings from their respective pencils reproduced on Plates 6 aud 7. To Miss V. Sheffield I am indebted for tlie original of fig. 63. | ||
To my friend Dr. F. P. Sandes, Sydney, I am indebted for | To my friend Dr. F. P. Sandes, Sydney, I am indebted for kind help in the revision of certain parts of the manuscript. | ||
{{Hill1910 footer}} | {{Hill1910 footer}} | ||
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Hill JP. The Early Development of the Marsupialia, with Special Reference to the Native Cat (Dasyurus Viverrinus). (1910) Quart. J. Micro. Sci. 56(1): 1-134.
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dasyurid
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The Early Development of the Marsupialia, with Special Reference to the Native Cat (Dasyurus Viverrinus)
(Contributions to the Embryology of the Marsupialia, IV.)
By
J. P. Hill, H.Sc.,
Jodrell Professor of Zoology and Comparative Anatomy, University of London, University College.
With Plates 1-9 and 2 Text-figs.
Table of Contents
Introduction
- Critical Review of Previous Observations on the Early Development of Marsupialia
- The Ovum of Dasyurus
- Structure of Ovarian Ovum
- Maturation and Ovulation
- Secondary Egg-membranes
- Uterine Ovum
- Cleavage and Formation of Blastocyst
- Cleavage
- Formation of Blastocyst
- Growth of Blastocyst and Differentiation OP THE Embryonal Ectoderm and the Entoderm
- Growth of Blastocyst
- Differentiation of the Embryonal Ectoderm and the Entoderm
- Establishment of the Definitive Embryonal Area
- Summary
- Chapter V. - Some Early Stages of Perameles and Macropus
- Chapter VI. - General Summary and Conclusions
- Chapter VII. - The Early Ontogeny of the Mammalia in the Light of the Foregoing Observations
- The Early Development of the Prototheria
- The Early Development of the Metatheria and Eutheria
- The Entypic Condition of the Eutherian Blastocyst
- Addendum
- List op References
- Explanation of Plates
Introduction
- "In mammalian embiyology very many surprises are yet in store for us" (Hubrecht, 08).
The present contribution contains an account of the nrincipal results and conclusions at which I have arrived after a somewhat protracted and much interrupted study of an extensive collection of early developmental stages of Marsupials, ranging from the fertilised egg to the blastocyst in which the two primary germ layers are definitely established. I believe I nm now able to give for the first time an account of early Marsupial ontogeny, based on the examination of an adequate material, and both consistent in itself and with Avhat we know of the early development in the other two Mammalian sub-classes. The material at my disposal was obtained during my tenure of office in the University of Sydney, and with the aid of grants from the Royal Society and of a George Heriot Research Fellowship. It represents the proceeds of some eight years collecting, and comprises a fairly complete series of stages of the native cat (Dasyurus viverrinus), together with a few early stages of other Marsupials, notably Perameles and Macropus.
Dasyurus proved in many ways a convenient subject for embryological purposes. It can readily be trapped in many places in New South Wales; it lives and breeds fairly well in captivity, and though always somewhat intractable, it can, owing to its size, be easily handled, and so may be subjected if necessary to daily exarainationd But it lias this great disadvantage, which it apparently shares with other Marsupials, that a very variable period intervenes between coitus and ovulation. As a consequence, the obtaining of any desired cleavage or early blastocyst stage is largely a matter of chance.^ It is true that the changes which take place in the pouch, in correlation with ovulation and the events connected therewith, do afford in the case of late pregnant females some indication of the stage of development likely to be met with, but these changes are at first of too indefinite a character to be of much service beyond indicating that ovulation may have taken place.
Dasyurus breeds but once a year, the breeding season extending over the winter months - May to August. One remarkable featui'e in the reproduction of Dasyurus, to which I have directed attention in a previous paper (Hill, ’00), may be again referred to here, and that is the fact that there is no correlation between the number of ova shed during ovulation and the accommodation available in the pouch. The normal number of teats present in the latter is six, though the pi-esence of one or two supernumerary teats is not uncommon; the number of ova shed at one period is, as a rule, far in excess of the teat number. I have, for example, several records of the occurrence of from twenty to twenty-five eggs, two of twenty-eight, one of thirty, and one of as many as thirty-five! (twenty-three normal blastocysts and twelve abnormal), there can be little doubt that Dasyurus, like various other Marsupials (e.g. Perameles, Macropus, etc.), has suffered a progressive reduction in the number of young reared, but even making due allowance for that, the excess in production of ova over requii’eraents would still be remarkable enough. Whether this over-production is to be correlated in any way with the occurrence of abnormalities during early development or not, the fact remains that cleavage abnormalities are quite frequently met with in Dasyurus.
- Perameles, on the other hand, though quite common in many parts of tlie State, is hy no means such a convenient type. It is much less easily trapped than Dasyurus, does not live nearly so well in captivity, and is pai'ticularly difficiilt to handle. I have to thank Mr. D. G. Stead, now of the Department of Fisheries, Sydney, for first directing my attention to the breeding habits of Dasyurus, and also for providing me with the first female from which I obtained segmenting eggs.
- For example, I obtained unsegmented ova from the uteri, four, five, six, seven and eight days after coitus, 2-celled eggs six and seven days after, 4-celled eggs eleven and eighteen days after. In one case the young were bom eight days after the last observed act of coitus, in another sixteen days after, and in yet another twenty days after.
Technique
As fixatives, I have employed for ovaries the fluids of Hermann, Flemming, Ohlmacher, and Zenker; for ova and early blastocysts, Hermann, Flemming, Perenyi, and especially picro-nitro-osmic acid (picro-nitric acid [Mayer] 96 C.C., 1 per cent, osmic acid 2 c.c., glac. acetic acid 2 c.c.) ; for later blastocysts, the last-named fluid especiall}'^ also picro-corrosive-acetic aud corrosive-acetic.
To facilitate the handling of ova and early blastocysts during embedding, I found it convenient to attach each specimen separately to a small square of pig’s foetal membrane by means of a dilute solution of photoxylin (1 to 2 per cent.), Orientation of the specimen was then easily effected during final embedding, under the low power of the microscope. The larger blastocysts were double-embedded in photoxylin and paraffin, the cavity of the blastocyst being tensely filled with the photoxylin solution by means of a hypodermic syringe fitted with a fine needle.
For the staining of sections, Heidenhain's iron-htematoxylin method proved the most satisfactory, and was almost exclusively employed. Entire portions of the blastocyst wall were stained either with Ehrlich's or Delafield's haematoxylin.
I am much indebted to Mr. L. Scbaeffer, of the Anatomical Department of the University of Sydney, and to Mr. F. Pittock, of the Zoological Department, University College, for invaluable assistance in the preparation of the photomicrographs reproduced on Plates 1 - 5, and also to Mr. A. Cronin, of Sydney, and Miss M. Rhodes, for the drawings from their respective pencils reproduced on Plates 6 aud 7. To Miss V. Sheffield I am indebted for tlie original of fig. 63.
To my friend Dr. F. P. Sandes, Sydney, I am indebted for kind help in the revision of certain parts of the manuscript.
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Contents: 1 Review of Previous Observations | 2 The Ovum of Dasyurus | 3 Cleavage and Blastocyst | 4 Blastocyst Growth Ectoderm Entoderm | 5 Early Stages of Perameles and Macropus | 6 Summary and Conclusions | 7 Early Mammalia Ontogeny | Explanation of Plates
Cite this page: Hill, M.A. (2024, April 19) Embryology Paper - Contributions to the embryology of the marsupialia 4. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_Contributions_to_the_embryology_of_the_marsupialia_4
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
