. The physiology of reproduction. Reproduction. FCETAL NUTRITION: THE PLACENTA 445 as in the mouse, an inversion of the germinal layers, but in the guinea-pig the amnio-embryonic vesicle is closed and separates the thickened trophoblast from the embryonic ectoderm (Fig. 108). With the growth of the blastodermic vesicle, the roof of the implantation cavity projects into the lumen of the uterus, and in time obhterates it by coming in contact and fusing, at the tenth day, with the mesometrial mucosa (Fig. 109). Here also the cellular tissue has developed at the expense of the glands, and the surf
. The physiology of reproduction. Reproduction. FCETAL NUTRITION: THE PLACENTA 445 as in the mouse, an inversion of the germinal layers, but in the guinea-pig the amnio-embryonic vesicle is closed and separates the thickened trophoblast from the embryonic ectoderm (Fig. 108). With the growth of the blastodermic vesicle, the roof of the implantation cavity projects into the lumen of the uterus, and in time obhterates it by coming in contact and fusing, at the tenth day, with the mesometrial mucosa (Fig. 109). Here also the cellular tissue has developed at the expense of the glands, and the surface epithelium disappears. At the fifteenth mes. FiGf. 109.—Implantation cavity of the guinea-pig. (Duval.) mes, mesometrial border ; I, uterine lumen. day the lumen reappears anti-mesometrially (Fig. 110). Thus a secondary decidua reflexa arises which rapidly thins and be- comes vacuolated in its inner half by a loss of tissue. The cause of the tissue excavation is uncertain ; it may be brought about by the large cells which, according to von Spee, are foetal and form a third layer of the trophoblast outside the plasmodiblast, and the disintegrated products are probably absorbed by the ovum. At the same time the vessels which penetrate the necrotic zone are opened, and blood is effused into the implanta- tion cavity. The placenta develops, as in the mouse, mesometriaUy. The. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marshall, F. H. A. (Francis Hugh Adam), 1878-1949; Cramer, William, 1878-1945; Lochhead, James. London, New York, Longmans, Green
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectreproduction, bookyea
