Paper - Contributions to the embryology of the marsupialia 4-Plates

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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.

  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
Online Editor  
Eastern quoll
Eastern quoll
Mark Hill.jpg
This historic 1910 paper by James Peter Hill describes marsupial development in the native cat (Dasyurus Viverrinus)



Note that native cat, eastern native cat, are historic names for the eastern quoll Dasyurus Viverrinus (D. viverrinus). The eastern quoll is a medium-sized carnivorous marsupial native to Australia.

  • Dasyurus - "hairy tail"

dasyurid

Modern Notes:

Australian Animal: echidna | kangaroo | koala | platypus | possum | Category:Echidna | Category:Kangaroo | Category:Koala | Category:Platypus | Category:Possum | Category:Marsupial | Category:Monotreme | Development Timetable | K12
Historic Australian Animal  
Historic Embryology: 1834 Early Kangaroo | 1880 Platypus Cochlea | 1887 Monotremata and Marsupialia | 1910 Eastern Quoll | 1915 The Monotreme Skull | 1939 Early Echidna

The Hill Collection contains much histology of echidna and platypus embryonic development.

Embryology History | Historic Disclaimer

Other Marsupials  
Monito del Monte Development | Opossum Development
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)

Explanation Of Plates 1-9

Illustrating Prof. J. P. Hill's paper on The Early Development of the Marsupialia, with Special Reference to the Native Cat (Dasyurus vi verrinus).


[All figures are from specimens of Dasyurus, unless otherwise indicated. Drawings were executed with the aid of Zeiss's camera lucida, except figs. 61-63, which were drawn from photographs.]

List of Common Reference Letters

Ab7i. Abnormal blastomei'e, fig. 37. alh. Albumen, eg. Coagulum. d. p. Discus proligerus. d. z. Deutoplasmic zone. emb. a. Embryonal area. emb. ect. Embiyonal ectoderm, ent. Entoderm. /. ep. Follicular epithelium. /. a. Formative area of blastocyst wall. /. c. Formative cell. /. z. Formative zone. i. c. Internal cell, fig. 34. Z. eat. Limit of extension of entoderm. Z. p. Incomjilete ai'ea of blastocyst wall at lower pole. p. b'. First polar body. p. b'. s. First polar spindle, p. V. s. Second polar spindle, p. s. Perivitelline space, s. m. Shell-membrane. sp. Sperm in albumen. Zr. ect. Non-formative or trophoblastic ectoderm (tropho-ectoderm). y.b. Yolk-body. z. p. Zona.

PLATE 1

Fig. 1. - Photo-micrograph (x 150 diameters) of the full-grown ovarian ovum, '27 X ‘26 mm. diameter. The central deutoplasmic zone (cZ. z.) and the peripheral formative zone (/. z.), in which the vesicular nucleus ('QS X '03 mni. diameter) is situated, are clearly distinguishable. The zona (z. p.) measures •0021-'0025 mm. in thickness. Outside it are the follicular epithelial cells of the discus proligerus (d.p.), which is thickened on the upper side of the figure, where it becomes continuous with the membrana granulosa. (D. v i v., 21 . vii . '04, Hermann's fluid and iron-hsematoxylin.)

Fig. 2. - Photo-micrograph ( X. 150) of ripe ovarian ovum (in which first polar body is separated and second polar spindle is present, though neither is visible in figure), '29 X '23 mm. maximum diametei'. FoUicle 1'4 X IT mm. diameter. The ovum exhibits an obvious polarity. Deutoplasmic zone {d. z.) in upper hemisphere ; formative zone (/. z.) foi-ming lower. (D. v i v., 14, 26 . vii . '02, Flemming's fluid and iron-haematoxylin.)

Fig. 3. - Photo-micrograph ( x 150) of ripe ovarian ovum ('28 x '24 mm. diameter) with first polar body (p. bK) and second polar spindle. First polar body, •026-‘03 x '01 mm. Second polar spindle, '013 mm. in length. (D. v i v., 14, 26 . vii . '02, Flemming's fli;id and ironhaematoxylin.)

Fig. 4. - Photo-micrograph (x 256) of ovarian ovum in process of growth (“pseudo-alveolar” stage). Ovum, ‘26 X '20 mm. diameter. Zona, •0017-‘002 mm. in thickness. (D. v i v., 14, 26 . vii . '02, Hermann, iron-haematoxylin.)

Fig. 5. - Photo-micrograph (X 1250) of peripheral i-egion of ripe ovarian ovum ('28 X T26 mm. diameter) with first polar spindle ('015 X '013 mm.). (D. v i v., 23 . vii . '02, Ohlmaicher's fluid, iron-haema toxylin.)

Fig. 6. - Photo-micrograph (x 1250) of peripheral region of ripe ovarian ovum ('26 X T8 mm.), showing first polar body (p. b'.) ('03 X •006 mm.). (D. v i v., 14, 26 . vii . '02, Flemming, iron-hfematoxylin.)

Fig. 7. - Photo-micrograph ( X 1250) of periplieral region of ovum, fig. 3, showing portion of first polar body (p. 5'.), and the second polar spindle. The dark body lying between p. 5'. and the surface of the ovum is a displaced red blood-corpuscle.

Figs. 8 and 9. - Photo-micrographs ( X about 84) of unsegmented ova, respectively '33 mm. and '35 mm. in diameter, from the uterus, taken immediately after their transference to the fixing fluid (picro-nitroosmic acid), showing the shell-membrane (s. m.), laminated albumen {alb.), with sperms (sp.), the zona (z. p.), perivitelline space {p. s.), and the body of the ovum, with its formative (/. z.), and deutoplasmic {d. z.) zones. (D. v i v., 15, 19 . vii . '01.)

Fig. 10. - Photo-micrograph ( X 150) of section of imsegmented ovum almost immediately after its passage into the uterus, showing the very thin sliell-inembvane externally (s. m.) (about '0016 mm. in thickness), the albumen {alb.), zona (z-i?.), and the deutoplasmic {d. z.) and formative (/. z.) zones of its cytoplasmic body. The male pronucleus is visible in the formative zone. Diameter of entire egg about '29 mm. (D. viv., 15, 19 . vii . '01, Picro-nitro-osmic and iron-hffimatoxylin.)

Fig. 11. - Photo-micrograph ( X 150) of section of unsegmented ovum from the uterus, slightly older than that of fig. 10. Diameter of entire egg in fresh state •34-'35 mm., of the ovum proper '3 X ‘28 mm. ; thickness of shell, -0024 mm. In the figure the female pronucleus is visible near the centre of the formative zone (/. z.), and the male pronucleus lies a little above it and to the right. The perivitelline space (jJ.s.) is pai-tiaUy occupied by coagulum. (D . viv., 21 . v . '03, f. Hermann, iron-hsematoxylin.)

PLATE 2

Fig. 12. - Photo-micrograph ( X 150) of an unsegmented ovum from the irterus, of the same batch as that of fig. 11, and '34 mm. in diameter. The two pronuclei are visible in the central region of the formative zone.

Fig. 13. - Photo-microgi-aph ( X 330) of uterine ovum. Stage of first cleavage spindle. Diameter, '315 mm. (D. viv., 1, 15 . vii . '01, f. Picro-nitro-osmic, iron-hiematoxylin.)

Fig. 14. - Photo-micrograph ( X about 78) of egg in the 2-celled stage, taken immediately after its transference to the fixing fluid. Lateral view. y. b. Yolk body. Diameter of entire egg about "34 mm. (D . viv., 1, 15 . vii . '01. Picro-nitro-osmic.)

Fig. 15. - Photo-micrograph (x about 78) of another 2-celled egg, seen from lower pole. Diameter, '35 mm. (D. viv., 4 B, 23 . vi . '02. Perenyi's fluid.)

Fig. 16. - Photo-micrograph (x about 78) of another 2-celled egg, of the same batch as preceding. End view, showing one of the two blastomeres and the yolk -body (y. b.).

Fig. 17. - Photo-micrograph (x 150) of vertical section of 2-celled egg, "34 mm. in diameter, showing the shell-membrane ('0064 mm. thick), traces only of the albumen, the zona (z.p.), and the two blastomeres (the left one measuring, from the sections, T6 x T8 x TO mm., its nucleus ‘031 X ‘027 mm. ; the right one, T6 x T9 X "09 mm., its nucleus, '03 x •028 mm.). Note the differentiation in their cytoplasmic bodies. (D . viv., 6, 21 . vii . '01, Picro-nitro -osmic and iron-hsematoxylin.)

Fig. 18. - Photo-micrograph (x 150) of vertical section of 2-celled egg, '32 mm. in diameter, with shell-membrane '005 mm. thick, showing the two blastomeres, and enclosed between their upper ends the yolk body {y. b.). (D . viv., 1, 15 . vii . '01, f. Picro-nitro-osmic, iron-htematoxylin.)

Figs. 19 and 20. - Photo-micrographs ( x about 70) of 4-eelled eggs taken immediately after transference to Perenyi's fluid. Fig. 19, side view, showing yolk-body (y. h.) ; fig. 20, polar view. Diameter of entire egg about -35 mm. (D . viv., 14 b, 18 . vi . '02. Perenyi.)

Fig. 21. - Photo-micrograph (x about 70) of another 4-celled egg, from the same batch as the preceding, seen from lower pole.

Fig. 22. - Photo-micrograph (x 150) of section of 4-ceUed egg of same batch as those of figs. 19 and 20. The two right and the two left blastomeres respectively form pairs, so that the plane of the first cleavage is parallel with the sides of tlie plate, that of the second with the top and bottom of the same. The two left blastomeres are still connected by a narrow cytoplasmic bridge. Thickness of shell, •0072 mm.

Fig. 23. - Photo-micrograph ( x 150) of a vertical section through a 4-celled egg. ‘35 mm. in diameter, showing two of the blastomeres and a small portion of the yolk-body {y. b.). Note, as in fig. 22, the marked diflierentiation in the cytoplasm of the blastomeres. (D. viv., 4, 27 . vi . '01. Picro-nitro-osmic, iron-hsematoxylin.)

Figs. 24 and 25. - Photo-micrographs ( x 140) of horizontal sections through a 16-celled egg, '38 mm. diameter, fig. 24 showing the eight larger, more yolk-rich cells of the lower (non-formative) ring, and fig. 25 the eight smaller, less yolk-rich cells of the upper (formative) ring. Shell ‘0075 mm. in thickness, yolk-body (not included in the figures) 'll X TO mm. in diameter. (D. viv., 3 b, 26 . vi . '01; 15, f and |. Picro-nitro-osmic and iron-hsematoxylin.)

Fig. 26. - Photo-micrograph (x 140) of a vertical section of an egg of the same batch and size as that represented in figs. 24 and 25, but with seventeen cells - formative = 9 (6 + [1 X 2] + 1) in division ; non-formative = 8. Two of the formative cells (/. c.) of the upper ring are seen enclosing between them the faintly mai'ked yolk-body {y. b.), and below them two of the much more opaque non-formative cells {tr. ect.) of the lower ring.

PLATE 3

Fig. 27. - Photo-micrograph (x about 76) of the just completed blastocyst, '39 mm. in diameter. From a spirit specimen. The dark spherical mass (eg.) in the blastocyst cavity is simply coagulum, produced by the action of the fixative (picro-nitro-osmic acid) on the albuminous fluid which fills the blastocyst cavity. (D. viv., 2 b, 16 . vii . '01.)


Fig. 28. - Photo-micrograph ( X about 76) of a blastocyst of the same batch as the preceding, •45 mm. in diameter. From a spirit specimen. eg. Coagulum.

Fig. 29. - Photo-micrograph (x about 75) of another blastocyst, •45 mm. diameter, of the same batch as the preceding, but taken immediately after transference to the fixative. Viewed from the upper pole. y. b. Tolk-body seen through the unilaminar wall.

Fig. 30. - Photo-micrograph ( X about 75) of a blastocyst of the same batch as the preceding, about '39 mm. in diameter, in which the cellular wall has not yet been completed over the lower polar region.

Fig. 31. - Photo-micrograph ( X 140) of a section of a blastocyst, •39 mm. diameter, of the same batch as the preceding and at precisely the same developmental stage, the cellular wall having yet to be completed over the lower polar region (l.p.). In the blastocyst cavity is seen the yolk-body (y. b.) partially surroixnded by a mass of coagulum (eg.). (D. viv., 2 B, 16 . vii . '01, m. = '39, Picro-nitro-osmic and iron-hsematoxylin.)

Fig. 32. - Photo-micrograph ( X 140) of another blastocyst, ^41 mm. in diameter, of the same batch as the preceding, also 'with the cellular wall still absent over the lower polar region. Shell-membrane ‘0075 mm. in thickness, y. b. Tolk-body. c. g. Coagulum. The cellular wall comprises about 130 cells.

Fig. 33. - Photo-micrograph ( X 140) of a blastocyst of the same batch as the preceding, with a complete unilaminar cellular wall. y. b. Yolkbody, in contact with inner surface of wall, in the region of the upper pole.

Fig. 34. - Photo-micrograph (x 100) of a section of a blastocyst •57 mm. in diameter, i. c. Internal ceU. (D . vi v., 29 . vi . '04, y . Pici^onitro-osmic.)

Fig. 35. - Photo-micrograph (x 100) of a section of a blastocyst, '73 mm. diameter, of the same batch as the pi^eceding, shell, ^0045 mm. thick.

Fig. 36. - Photo-micrograph (x 100) of a section of a blastocyst -66 mm. diameter, of the same batch as the pi-eceding. Lower hemisphere opposite yolk-body {y. b.) formed of larger cells than upper. Hermann fixation.

Fig. 37. - Photo-micrograph (x 140) of section of an abnormal vesicle, 397 mm. diameter of the same batch as the normal vesicles represented in figs. 27-33. abn. large binucleate cell, regarded as a blastomere of the lower hemisphex^e which has failed to divide in noi^mal fashion, cf . text, p. 42.

PLATE 4

Fig. 38 - Photo-micrograpli ( x 10) of entire blastocyst 4'5 mm. diameter to show the junctional line {j. 1.) between formative and nonformative regions. From a spirit specimen. (D . viv., /3, 25 . vii . '01. Picro-nitro-osmic.)

Fig. 39. - Photo-micrograph ( x about 10) of an entire blastocyst, 4'5 mm. diameter with distinct embryonal area {emh. a.). (D. viv., 5, 18 . vii . '01.)

Fig. 40. - Photo-micrograph { X 10) of entire blastocyst about 5 mm. diameter showing embryonal area' {emh. a.), peripheral limit of entoderm (1. ent.), and the still unilaminar region of the wall {tr. ect.). (D. viv., 8 . vi . '01.)

Fig. 41. - Photo-micrograph ( x 150) of an in toto preparation of the wall of a blastocyst of 3'5 mm. diameter. (D . viv., 16, 21 . vii . '01.)

Fig. 42. - Photo-micrograph (x 150) of an in toto preparation of the wall of a blastocyst of 3'25 mm. diameter, j. 1. Junctional line between the formative (/. a.) and non-formative {tr. ect.) regions of the wall. (D. viv., 24 . vii . '01.)

Figs. 43 and 44. - Photo-micrographs (x 150) of in toto preparations of the wall of 4'5 mm. blastocyst showing the jimctional line between the formative (/. a.) and non-formative {tr. ect.) regions. (D. viv., P, 25 . vii . '01. Picro-nitro-osmic and Ehrlich's hsematoxylin )

Fig. 45. - Photo-micrograph ( x 150) of a corresponding preparation of the wall of a more advanced 4'5 mm. blastocyst ('99 stage), in which the two regions of the wall are now clearly distinguishable. (D. viv., 8.7. '99. Picro-nitro-osmic, Ehrlich's hsematoxylin.)

Fig. 46. - Photo-micrograph ( x 150) of a corresponding preparation of a slightly more advanced blastocyst ('04 stage). (D. viv., 6 . 7 . '04. Picro-nitro-osmic, Ehrlich's hsematoxylin.)

PLATE 5

Fig. 47. - Photo-micrograph (x 150) of an in toto preparation of the formative region of a 6 . 7 . '04 blastocyst, showing the proliferation of spherical interaal cells refeiTed to in the text, p. 53.

Fig. 48. - Photo-micrograph ( X 150) of an in toto preparation of the wall of a vesicle of the same batch as that represented in fig. 39, in which a small part of the junctional line between the embryonal ectodenn and the extra-embryonal {tr. ect.) is visible, the free edge of the entoderm {ent.) not having reached it. (D. viv., 5, 18 . vii . '01. Picronitro-osmic, Ehrlich's hsematoxylin.)


Fig. 49. - Photo-micrograpli ( X 150) of a con-esponding preparation of a vesicle of the same batch as the preceding, in which the wavy and irregularly thickened free edge of the entoderm {ent.) practically coincides with the junctional line and so conceals it from view.

Fig. 50. - Photo-micrograph (x 150) of an in to to preparation of a vesicle (8 . vi . '01 batch) viewed from the inner surface as in the corresponding preceding figures. The entoderm in the region of the embryonal ax-ea has been removed, so that one sees the inner surface of the embryonal ectoderm [emh. ect.) ; it is still in situ, though not in a quite intact condition over the adjoining portion of extra-embryonal ectoderm. The entoderm has not yet extended over the region indicated by the reference line to tr. ect., so that here the extra-embryonal ectoderm is cleai-ly visible. The jimctional line is apparent. (D. viv., 8 . vi . '01. Picronitro-osmic. Ehrlich's hsematoxylin.)

Fig. 51 (Plate 3). - Photo-micrograph ( X 310) of a section of a 30celled egg of Perameles obesula; egg b, '24 X '23 mm. diameter, showing the xinilaniinar layer formed by the blastomeres.

Fig. 52 (Plate 3). - Photo-micrograph (x 240) of a section of a blastocyst of P. nasuta '29 X •26 mm. diameter, showing the shellmembrane {s.vi.), zona (z.p.), and the unilaminar celhxlar waU. The portion of the latter adjacent to the reference lines is composed of smaller but thicker cells than the remainder.

PLATE 6

Figs. 53 and 54. - Drawings ( X 84) of a 6-celled egg '34 mm. diameter, fig. 53 showing a side view and fig. 54 a view from the lower pole. Observe the characteristic I'ing-shaped arrangement of the blastomeres. y. b. Yolk -body, the shell-membrane, albumen layer with sperms included, and the zona are readily distinguishable. Outlines drawn with the aid of the camera lucida immediately after transference of the egg to the fixing fluid. (D . viv., 22, 16 . vii . '01.)

Figs. 55 and 56. - Drawings ( X about 88) of a 16-ceUed egg (about ‘37 mm. diameter) as seen fx'om the side and lower pole respectively, from the same batch as the eggs represented in figs. 24, 25, and 26. The charactei'istic aii'angement of the blastomex'es in two sxxpex'imposed, open x'ings (each of eight cells) and the diffex'ence in size between the cells of the two riixgs are evident. The ix'x-egxxlar body (c.g.) seen ixx the cleavage cavity in fig. 56 is a mass of coagxxluixx. Dx'aunx from a spix'it specimen. The albumen layer as represented in fig. 56 is too thick. (D. viv., 3 B, 26 . vi . '01.)

Figs. 57 and 58. - Drawings (x about 85) of a 12-celled egg (-38 xixm. diameter) as seen from the side axxd lower pole respectively. Four of the blastomeres of the 8-ceHed stage have already divided (4 + 4x2) = 12. From a spirit specimen and from same batch as preceding.

Fig. 59. - Drawing ( x about 88) of a 31-celled egg ('375 mm. diameter) as seen from the lower pole. From a spirit specimen and fi-om the same batch as the preceding. The irregular body in the blastocyst cavity is formed by coagulnm. Formative cells = 16; non- formative = 14 + 1 in division.

Fig. 60. - Drawing ( X about 88) of another 31-celled egg ('375 diameter) from the same batch as the preceding. Side view.

Fig. 61. - Drawing (x 100) of an entire blastocyst (‘39 mm. diameter) from the same batch as those shown in figs. 27-29.

Fig. 62. - Drawing ( x about 80) of an entire blastocyst (‘4 mm. diameter) from the same batch as the preceding.

Fig. 63. - Drawing (x 80 of an entire blastocyst ('6 mm. diameter) made from a photogi'aph taken directly after transference of the specimen to the fixing fluid. Cells of lower hemisphere with imich more marked perinuclear areas of dense cytoplasm than those of the upper. D. viv., 2, 11 . vii . '01.)

Fig. 64. - Section of the wall of a blastocyst, 2'4 mm. diameter (x 630). (D. viv., 7 . vi . '01.)

Figs. 65, 66, 67. - Drawings (x 630) of small portions of in toto preparations of the formative region of 6 . 7 . '04 blastocysts to demonstrate the mode of origin of the primitive entodermal cells {ent., fig. 67). Fig. 65 shows a dividing entodermal mother-cell in position in the unilaminar wall, siuTounded by larger lighter staining cells (prospective embryonal ectodermal cells). In fig. 66 is seen a corresponding cell, a poi-tion of whose cell-body has extended inwards so as to underlie (overlie in figure) one of the ectodermal cells of the wall. . In fig. 67 are seen two entodermal cells, evidently sister-cells, the products of the division of such a cell as is seen in figs. 65 or 66. One of them (the upper) is still a constituent of the unilaminar wall, the other {ent.) is a primitive entodermal cell, definitely internal. (D . viv ., 6 . 7 . '04. Picronitro-osmic, Ehrlich's haematoxylin.)


PLATE 7

Figs. 68, 69, 70. - Drawings (x 630) of portions of preparations similar to the above. For description see text. (D. viv., 6, 7, '04.)

Fig; 71. - Drawing (x about 630) of a portion of an in toto preparation of the formative region of an '01 blastocyst showing two primitive entodermal cells, one of them in division. (D. viv., (3, 25 . vii . '01. Picro-nitro-osmic and Ehrlich.)


Fig. 72. - D rawing (x 630) corresponding to the above, from the formative region of a 6 . 7 . '04 blastocyst, also showing two primitive entodermal cells, evidently sister-cells.

PLATE 8

Figs. 73, 74, 76. - Sections of the formative region of 6.7. '04 blastocysts, showing the attenuated shell-membrane, the unilaminar waU, and in close contact with the inner surface of the latter, the primitive entodermal cells {ent.) ( X 630).

Fig. 75. - Section corresponding to the above, showing an entodermal mother-cell {ent.), part of whose cell-body nndei'lies the adjacent ectodermal cell of the wall. The spheroidal inwardly projecting cell on the left is probably also an entodermal mother-cell (x 630).

Fig. 77. - Section ( x 630) of the non-formative I'egion of a 6 . 7 . '04 blastocyst.

Fig. 78. - Section ( X 630) of the embryonal ai'ea, and the adjoining portion of the still imilaminar extra-embryonal region of a blastocyst of the 5 . '01 stage, emb. ect. Embryonal ectoderm, ent. Entoderm, tr. ect. Extra-embryonal ectoderm (tropho-ectoderm). The position of the junctional line is readily recognisable. (D . vi v. , 5, 18 . vii . '01. Picronitro-osmic and Delafield's hsematoxylin.)

Fig. 79. - Section (x 630) through the corresponding regions in an 8 . vi . '01 blastocyst. Note the thickening of the embryonal ectoderm {emb. ect.), and the peripheral extension of the entoderm {ent.) below the tropho-ectoderm. (D. viv., 8 . vi . '01. Picro-nitro-osmic and Lelafield.)

Fig. 80. - Section (x 600) through the formative (embryonal) region of a blastocyst of P. nasuta, 1‘3 mm. in diameter. It is thicker than that of the Dasyure blastocyst at the corresponding stage of development ; the primitive entodermal cells are well mai-ked.

Fig. 81. - Section ( x 600) corresponding to the above from another 1-3 mm. blastocyst of P. nasuta, of the same batch as the preceding, but apparently very slightly earlier, the entodermal cells being stiU in process of separating from the unilaminar wall. ent. Entoderm, tr. ect. Tropho-ectoderm.

PLATE 9

Fig. 82. Section (x about 430) of a section of a blastocyst of M. ruficollis -35 mm. in diameter, showing the major portion of the formative region (/. a.) and a small portion of the non-formative {tr. ect.). The shell-membrane varies in thickness in the sections from (J05 min. over the former region to '003 mm. over the latter.

Figs. 83, 84, 85. - Drawings ( X 630) of small portions of the formative (and in fig. 83 of the adjoining portion of the non-formative) region of the above blastocyst of M. ruficollis more highly magnified, ent. Primitive entodermal cells. Note in fig. 83 a cell of the wall in division, the axis of the spindle being oblique to the surface.



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)

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. (2019, September 18) Embryology Paper - Contributions to the embryology of the marsupialia 4-Plates. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_Contributions_to_the_embryology_of_the_marsupialia_4-Plates

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