A text-book of obstetrics / by J. Clarence Webster.

  • John Clarence Webster
Date:
1903
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of obstetrics / by J. Clarence Webster. Source: Wellcome Collection.

    75/810 page 65
    area, forming the main thickness of the placenta. This area is a space which is almost entirely occupied with projections of the chorion, forming the villus-stems and villi, which vary in size, shape, and structure. Many of the large stems are attached to the decidual layer; the great majority of the small villi, however, hang free like the branches of atree. Surrounding the villi is maternal blood, which gives the dark-red color to the placenta. Ordinarily the intervals between the villi in which the maternal blood is found are termed “ intervillous spaces,” but it must be clearly understood that these spaces are in free communication. The expression. “intervillous space” is, therefore, more accurate. In the angle at the edge of the placenta very few villi may exist in some parts, so that the appearance of a sinus is produced, and, indeed, it has been termed the cercular sinus. No special name should be given to it, however. It is merely the marginal portion or the intervillous space, and never extends as a direct sinus around the placenta, but is interrupted at irregular intervals by a well-marked development of villi. Besides the villus-stems and villi sections of buds and irreg- ular masses of syncytium growing from the chorionic membrane and villi are noticed. In many parts, where the free ends have been divided, the appearance is presented of masses lying free in the maternal blood. Here and there several villi closely pressed RC CUne Ma bereUteacCloss me OMe ol tiecesare embcddedin. ibrin, others are not. These are different forms of the Ze//knoten, which I have previously described. Portions of fibrin are also found on the surface of a number of villi. Besides these structures are noticed elevations of the decidual layer forming the maternal surface, and generally termed decidual septa. They are directed perpendicularly or obliquely toward the fetal surface of the pla- centa, and are for the most part very short; they rarely extend into the intervillous space for any considerable distance. Some- times, near the edge of the placenta, they may nearly reach the chorionic mémbrane. Villi are attached to them as well as to the general surface of the decidua. Leopold and others consider that these are of great structural importance, and suppose that fixation villi are chiefly attached to them. Extensive study of the placenta proves this view to be wrong. These decidual projections vary greatly in their development, being usually short, and often very scanty. They have no special significance in relation to the attachment of the villi. Often sections across free ends of such projections may be noticed, giving the appearance of portions of decidual tissue lying free in the maternal blood of the intervillous space. Occasion- ally such a section may include a number of villi attached to the decidual tissue or closely pressed against it; varying quantities 5
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