Contributions to the study of the early development and imbedding of the human ovum.
- Bryce, Thomas Hastie, 1862-1946.
- Date:
- 1908
Licence: In copyright
Credit: Contributions to the study of the early development and imbedding of the human ovum. Source: Wellcome Collection.
Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.
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![(4) The Plasmodium and necrotic zone of the decidua are not every- where directly in contact with one another; a union between the two occurs only here and there; elsewhere a space is left between the two containing red blood corpuscles and leucocytes. There is no indication that the wall of necrotic tissue is being absorbed by phagocytosis in the strict sense of the term; the appearances suggest rather solution by enzymes produced by the troplioblast. On the whole we are inclined to conclude that these elements are derived from the necrotic zone of the decidua; that they are in short decidual cells set free in the process of absorption of the necrotic tissue. It must be admitted however that there is no histological criterion by which it can be absolutely determined whether they are maternal or foetal derivatives.^ THE CONTENTS OF THE BLASTOCYST THE MESOBLAST. The cavity of the vesicle is occu])ied by a very delicate cellular reticulum, or loose syncytial tissue which has the characters of mesenchyme. It represents the earliest stage yet observed of the mesoblast. This mesenchymatous tissue shows no signs of cleavage into a parietal and a visceral layer; it is not yet arranged in a definite and denser layer round the wall of the vesicle, nor are there any processes of it indenting the wall. The constituent cells of the mesoblast are minute, i-ounded or stellate elements united together by very delicate protopUismic threads. They are brought out in the drawing reproduced in Plate iii, Fig. 3, but the network which thej' form is somewhat obscured by the delineation, in the ' Since the abuve was written we liave had the opportunity of seeing a demonstration by Graf V. Spee of the early phases of placentation in the guinea-pig, at the meeting of the Anatomische Gesellschaft in Berlin (April 2.3rd, 1908). Graf v. Spee showed that in the guinea- pig there is a layer of cells of foetal origin outside a plasmodial formation, which, though less extensive, has the same character as the plasmodium in our human ovum,— in short, that there are three layers of the trophoblast. Until his account of his preparations is published we can do no more than point out that Graf v. Spee's lesearches may possibly necessitate some modification of our interpretation of these elements.](https://iiif.wellcomecollection.org/image/b21506875_0034.jp2/full/800%2C/0/default.jpg)
