Book - The Development of the Albino Rat 14

From Embryology
Embryology - 18 Dec 2017    Facebook link Pinterest link Twitter link  Expand to Translate  
Google Translate - select your language from the list shown below (this will open a new external page)

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)

Huber GC. The Development of the Albino Rat (Mus norvegicus albinus). (1915) J. Morphology 26(2).

Normal: Introduction | Materials and Methods | Ovulation, Maturation and Fertilization | Pronuclear Stage | Segmentation Stages | 2-ceIl stage | 4-ceIl stage | 12 to 16-ceIl stages | Summary of segmentation stages | Completion of segmentation and blastodermic vesicle formation | Blastodermic vesicle | Late stages blastodermic vesicle | Egg-cylinder formation | Late stages in egg-cylinder | Conclusions | Literature cited | Figures
Abnormal: Introduction | Half Embryos in Mammalia | Degeneration of ova at the end of segmentation | Incomplete or retarded segmentation | Abnormal segmentation cavity formation | Degeneration of ova as a result of pathologic mucosa | Imperfect development of ectodermal vesicle | Two egg-cylinders in one decidual crypt | Conclusions | Literature cited
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)

Two Egg-Cylinders in One Decidual Crypt

The ova portrayed in figure 10 present a condition which must be regarded as exceedingly rare, since it represents the only instance of this condition observed in the extended series of preparations of the various stages of the development of the albino rat from the end of the first to the end of the ninth day after insemination, in my possession. This preparation is from rat No. 87, 9 days after the beginning of insemination. The uterus of this rat contained, other than the preparation here considered, six egg-cylinders of normal develojiment, all showing a stage which is slightly older than that shown in figure 31, Part I, in that the mesoderm shows further development than is shown in that figure. In the preparation here figured there are found two egg-cylinders enclosed within the same decidual crypt. This figure, which is drawn by combining the drawings made from two sections, is reproduced at a magnification of 150 diameters, while all of the other figures portraying sections of ova, both in Part I and in Part II of this communication, are reproduced at a magnification of 200 diameters. This should be borne in mind when comparing this figure with the others. In figure 10, the lower portion of the large egg-cylinder to the level of the lower end of the smaller one was drawn from one section, while the remainder of the figure was drawn from the fourth following one. The adjustment was made by overlapping in the camera lucida drawing ( X 600) the sharp mesometrial border of the primary embryonic ectoderm of the larger egg-cylinder. Scarcely any adjustnu'iit was found necessary, none of the riji;lit wall of the lar<2;er esg-fvlindor, and only \'ei\v sji^litiy so of its loft wall. The slijiiit de\'iation from the longitudinal axis of the larger eggeylinder made the pi-oeedure desicable. It is thought tliat the figui'e as ])res(>nte(l gi\'(>s correctly the size of the respective eggcylinders, and in all essentials, theii- I'elations; the greatei- j)aii of the figure having been drawn from one section, lioth of the egg-cylinders reveal normal structure for the stages of development attained. The larger one is cut in the coronal plane, as is readily determined by the distribution of the mesoderm, one side representing a mirror picture of the othei". The direction of section in the smaller egg-cylinder, except that it is longitudinal, is not to be determined, since before the anlage of the mesoderm, a bilateral symmetry cannot be recognized in sections. Since these two egg-cylinders are in all essentials of normal form and structure, and since their structure is clearly brought out in the figure, an extended description of them at this place seems uncalled for. For respective stages the reader is referred to Part I.


Attention may be drawn, however, to the fact that the visceral entoderm on the contiguous surfaces of the two egg-cylinders is less fully difTerentiated, and shows less absorption of the maternal hemoglobin than is seen on the exposed or free surfaces, this, no doubt, for mechanical reasons. Further, that in the region where the two egg-cylinders are in contact, the parietal ectoderm of each can be traced as a distinct layer to the bases of the respective ectoplacental cones, showing that each developed from a separate ovum. The ectoplacental cones are for a short distance distinct. In tracing the sections through the series the impression is gained that the ectoplacental cone of one of the eggcylinders o\'erlaps that of the other in such a way that in the plane of the sections obtained, one seems continuous with the other, as represented in the figure. The boundary between the two is not distinct, and it would seem that as a result of pressure, partial fusion of the two had taken place. The presence of two egg-cylinders, enclosed within a single decidual crypt, as shown in this figure, with one of them having much smaller size and representing a younger stage of development, I believe is not to be explained on the supposition of superfecundation or superfoetation. The record for this rat does not show insemination on successive days.


At The Wistar Institute, after all of the supposedly successful matings of albino rats, the females rats are caged apart from the males. The smaller egg-cylinder, though appreciably smaller, is in stage of development separated from the other by a time interval of perhaps less than 24 hours. It presents a stage of development which is comparable to C of figure 27 (8 days) and except for size, to the one figured in figure 29 (8 days, 17 hours) of Part I. It is believed that in this case both ova were seminated at about the same time, and proceeded through normal segmentation and that on reaching the lumen of the uterus during the fifth day they became lodged in close proximity in the same mucosal fold. With the development of the decidual crypts, both became enclosed within the same crypt, at perhaps slightly different levels. In further development one blastodermic ^'esicle dominated the other and from about the se\'enth day on, one de\'eloped and differentiated more rapidly than the other. Had development continued, two distinct embryos, \/ith separate amniotic cavities, attached to the same placenta, would have been formed, with one embryo large and more fully de\'eloped than the other. From mere difference in size and of development of embryos in the same litter it is not warranted to postulate superfecundation nor superfoetation. I am of the opinion that usually when two morula masses are lodged in close proximity in the same mucosal fold, one or the other degenerates (fig. 2, A) and that the normal development of both, as in the preparation shown in figure 10, is of very rare occurrence.

Conclusions

A study of the abnormal or pathologic ova met with in the extended series of preparations covering the first ten days of the development of the albino rat, enables grouping them in two main classes:

a. Such in which all of the ova of a given rat show, or are associated with, abnormal development.

b. Such in wliich a siMj>;l{> abiionnal oi- patliolo^ic oxiiin is found in tho same uterus along with an axcragc niinihcr ol n()i'niall>' (IcncIoixmI oN'a.


When all the ova in a given uterus show abnormality, the presumption seems warranted that th(» underlying cause of the abnormality is to be sought in an altered or pathologic condition of the uterine mucosa. In tlu^ instances observed, the presence of maternal blood with many phagocytic leucocytes was noted in the lumen of the uterus, adhering to and surrounding the ova. From the study of sections of the utei'i of an ai)i)i'e('iab!(' ininibcr of albino rats, in which insemination and su]:)posedly semination seemed normal, but in which on comi)lete serial sectioning of the uterine tubes no ova were found, but in the lumen of the uterine tubes of which the presence of maternal blood and phagocytic leucocytes was noted, the conclusion seems warranted that death and complete absorption of ova, after a given stage of normal development has been reached, may occur. In sucli cases, one may with propriety speak of faulty implantation. due to altered or pathologic condition of the uterine mucosa, even in cases where no actual implantation would have occurred in corresponding normal stages. In the two rats (Nos. 91 and 104) in which this condition was observed, the decidual crypts were shallow and not developed to the extent normal for the respective stages, evidencing the abnormal condition of the mucosa.


In cases in which a single abnormal or pathologic ovum is found in the uterus along with several normal ova, the presumption seems justified that the underlying cause responsible for the abnormal development is to be sought in the ovum itself, and not in its environs.


Abnormal developmental stages, interjireted as due to irregular or retarded segmentation, irregular or abnormal segmentation cavity formation, and retarded development of the ectodermal node and primary embryonic ectoderm, where only a single ovum shows abnormal development in a uterus containing the average number of ova presenting normal development, are difficult to explain on the assumption that extraneous influences affecting a single ovum are operative. Practically all of the abnormal ova of the class described, and especially is this true for older stages, present normal relations to the uterine mucosa and the walls of the decidual crj^pt after implantation, and so far as may be determined by structure, give evidence of normal absorption of maternal hemoglobin in stages in which such absorption is pertinent. It may be argued that a single ovum may be less favorably placed in relation to embryotroph or pabulum, and as a result of unfavorable nutrition, develop abnormally. This is difficult to conceive for stages in which the ova lie free in the lumen of the uterus, namely, to about the beginning of the seventh day after the beginning of insemination, when embryotroph or pabulum must be relatively evenly" distributed. The presumption, it would seem to me, in such cases is in favor of regarding the primary cause of the abnormal development as inherent in the ovum.


Separation of the first two blastomeres and the presence of two egg-cylinders in a single decidual crypt are regarded as chance findings and as of rare occurrence, since each was met with only once in the material at hand.

Literature Cited

Literature on pathologic ova of the albino rat is lacking. For the literature of all but the more recent work, dealing with comparative experimental teratology, the bibliographies accompanying the chapters of O. and R. Hertwig may be consulted; for that dealing with the pathology of human ova, the bibliographies accompanying the contributions of F. P. Mall may be consulted.


Hertwig, O. 1906 ^Nlissbildung und Mehrfachbildung, die durch Storung des ersten Entwicklungsprozesse hervorgerufen werden. Hertwig's Handbuch der vergleichenden und experimentellen Entwickelungslehre der Wirbeltiere, Bd. 1, Part 1; Fischer, Jena.

Hertwig, R. 1906 Der Furchungsprozess. Hertwig's Handbuch,Bd. 1, Part 1.

Mall, F. P. 1900 \^'elch Festschrift, Johns Hopkins Hospital Reports, vol. 9. 1903 Vaughan Festschrift, Contributions to medical science, G. Wahr, Ann Arbor.

1908 A study of the causes underlying the origin of human monsters. Jour. Morph., vol. 19.
1910 The pathology of the human ovima. Keibel and Mall, "Manual of Human Embryology." Lippincott Company, Philadelphia.



Normal: Introduction | Materials and Methods | Ovulation, Maturation and Fertilization | Pronuclear Stage | Segmentation Stages | 2-ceIl stage | 4-ceIl stage | 12 to 16-ceIl stages | Summary of segmentation stages | Completion of segmentation and blastodermic vesicle formation | Blastodermic vesicle | Late stages blastodermic vesicle | Egg-cylinder formation | Late stages in egg-cylinder | Conclusions | Literature cited | Figures
Abnormal: Introduction | Half Embryos in Mammalia | Degeneration of ova at the end of segmentation | Incomplete or retarded segmentation | Abnormal segmentation cavity formation | Degeneration of ova as a result of pathologic mucosa | Imperfect development of ectodermal vesicle | Two egg-cylinders in one decidual crypt | Conclusions | Literature cited
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)

Cite this page: Hill, M.A. 2017 Embryology Book - The Development of the Albino Rat 14. Retrieved December 18, 2017, from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_The_Development_of_the_Albino_Rat_14

What Links Here?
© Dr Mark Hill 2017, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G