Paper - A very Young Human Embryo found embedded in a "Decidual Cast" of the Uterus

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Waterston D. A very young human embryo found embedded in a "decidual cast" of the uterus. (1914) Proc R Soc Med., 7: 353-7. PMID 19978039

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This historic 1914 paper by Waterston describes a very early embedding human embryo.

Carnegie Staging: A 27 somite stage embryo would be similar to a Carnegie stage 12 (26 - 30 days), caudal neuropore closes, Somite Number 21-29.

David Waterston
David Waterston (1871-1942)

See also by this author:

Waterston D. A very young human embryo found embedded in a "decidual cast" of the uterus. (1914) Proc R Soc Med., 7: 353-7. PMID 19978039

Waterston D. A human embryo of twenty-seven pairs of somites, embedded in decidua. (1914) J Anat Physiol., 49(1): 90-118 PubMed 17233016 | PMC1288995

Waterston D. Developmental changes in the pericardium, the mesocardia, and the pleural sacs in the human embryo. (1915) J Anat Physiol., 50(1): 24-9. PMID 17233049

Waterston D. The development of the heart in man. (1917) Trans. Roy. Soc. Edin., 7(2): 258-302.

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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)

A very Young Human Embryo found embedded in a “Decidual Cast” of the Uterus

David Waterston
David Waterston (1871-1942)


By David Waterston, M.D.

Professor of Anatomy, King’s College, London.


The special interest attached to the specimen lies in the fact that a Very young human embryo was found embedded in the wall of a decidual cast of the uterus, and that the sections and the models show an early stage of the embedding of the embryo and of the formation of the placenta from the chorionic villi and decidua. The embryo is almost precisely 3 mm. in length, and its age I estimate as about 3 weeks.


The clinical history has been already published by Professor B. P. Watson and Mr. Henry Wade— who obtained the specimen, and to whom I am indebted for the opportunity of examining and reconstructing the embryo and the annexa—in the Journal of Obstetrics and Gynwcology of the British Empire,[1] and only a few of the main facts need be mentioned here.


The cast was passed from the uterus ten days after a missed period by a woman who had had repeated abortions. It was found to represent the whole of the lining membrane of the uterus, and was hollow. Projecting into the lumen was a small, pea-like nodule, 8 mm. in diameter, and, on the supposition that this nodule might contain an early embryo, the nodule was removed, embedded, and cut in serial sections. The authors were rewarded by finding that their surmise was correct, and, by great good fortune, the sections cut the embryo transversely to its long axis. A wax plate reconstruction model of the embryo and of the adjacent zone of chorion and the decidua at 50 diameters magnification was prepared in my laboratory, and other reconstructions of the embryo were also made at a magnification of 200 diameters.


The form of the embryo and its yolk-sac and body-stalk and the adjacent portions of the chorion and decidua are brought out so clearly in the models that little description of them it necessary. The first model (fig. 1) represents the segment of the “ pea-like nodule” in which the embryo lay. The smooth surface is the free surface which projected towards the uterine cavity——in other words, the uterine aspect of the decidua capsularis, which is seen to be thin and uniform in character. At its margin it passes into the decidua marginalis, and this in turn connects it with the decidua basalis. The surface remote from the observer is rough and shaggy, and is the aspect of the decidua which had separated from the uterine wall. The separation had taken place in the stratum spongiosum.


The histology of the decidua need not be described in detail beyond stating that the “ decidual reaction” was well marked, and that the surface of the decidua next to the chorion showed the “ Nitabuch fibrin stria,” a fibrinous or possibly necrotic layer, produced apparently by the syncytial layer of the chorion. Within the complete decidual capsule lies the chorion. The chorionic vesicle filled the “implantation cavity ” almost completely. It was studded with villi, which were very numerous indeed on the surface towards the decidua basalis, but few and scattered on the aspect in contact with the decidua capsularis.

Waterston1914 fig001.jpg

Fig. 1. Reconstruction model of the portion of the decidua containing the embryo. Original model x 50. Reduced to one-third.


The second figure (fig. 2) shows the decidua capsularis removed, and the external surface of the chorion. The cavity of the chorionic vesicle contained not only the embryo, yolk—sac, and body-stalk, but the remainder of the cavity was filled with the “magma réticulée” of Eternod, _a loose, fibrinous network, which is probably a precipitation deposit, and not organized (see fig. 4). The chorionic wall was already well vascularized by the branches of the umbilical vessels.


The next figure (fig. 3) shows the appearances seen after removal of a portion of the chorionic wall. The embryo is seen lying on its right side enclosed in the amnion, with a large yolk-sac ventrally, and the body-stalk passing from its trunk to the chorionic wall. The relation of these parts is well brought out by a transverse 'section at the level of the body-stalk, and the same section shows the blood-vessels of the embryo and the internal structure at this level (fig. 4).

Waterston1914 fig02.jpg

Fig. 2. Same model, after removal of decidua capsularis.

The structure of the embryo I have worked out in detail, and the results will be published in the Journal of Anatomy and Physiology for October.


The principal results of my investigations, in so far as they bear upon the early implantation of the embryo, may be summed up as follows: At the third week the whole chorionic vesicle is embedded in the decidual lining of the uterus, and lies in a‘ cavity which may be termed the implantation cavity. The layer of decidua which intervenes between this cavity and the lumen of the uterus is the decidua capsularis, while its floor is the decidua basalis. At this stage there is no sign of a “ penetration aperture” or “Reichert’s scar” in the decidua capsularis. The chorionic vesicle is freely covered with villi, and consists of an outer two-layered ectoderm wall, lined by mesoderm. The cavity of the chorionic vesicle contains a precipitation deposit or “magma ” The embryo and yolk-sac lie in the chorionic cavity, and the body of the embryo is attached to the chorionic wall by a stalk of mesoderm—the “ body-stalk ”—in which lie the umbilical vessels passing between the embryo and the chorion. The yolk-sac is in continuity with the primitive alimentary canal of the embryo, and there is therefore a wide vitello-intestinal connexion, with the vitelline arteries and veins lying on each side and ramifying freely on the wall of the yolk-sac. The body wall of the embryo is continuous with the amnion round the margins of the wide umbilical orifice, through which pass the vitellointestinal connexion and the vitelline vessels.

Waterston1914 fig03.jpg

Fig. 3. Appearances seen after removal of a portion of the chorionic wall.

Waterston1914 fig04.jpg

Fig. 4. A very Young Human Embryo found embedded in a “ Decidual Cast" of the Uterus.


  1. Journ. Obstet. and Gyaec. Brit. Empire, 1910, xvii, p. 103.

The PRESIDENT (Dr. W. S. A. Griffith) desired to thank Professor Waterston for his demonstration, and to congratulate him on the admirable models which he had with so much labour constructed. He also inquired if it would be practicable to have some reproductions made for demonstration purposes—they would be invaluable both to teachers and students. Dr. Griffith was sure that the appeal for material which Professor.Waterston had made would be responded to by all who appreciated the value of the work he was engaged in.



Cite this page: Hill, M.A. (2019, July 19) Embryology Paper - A very Young Human Embryo found embedded in a "Decidual Cast" of the Uterus. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_A_very_Young_Human_Embryo_found_embedded_in_a_%22Decidual_Cast%22_of_the_Uterus

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