. On the anatomy of vertebrates [electronic resource] . uptured orifice, fig. 566, b, b. In theCow and Sheep such altered i Graafian follicle assumes a brick-red colour; in the Sow a yellowish brown; and in the Womanthe brighter colour led to its being called a i corpus luteum. Inher the walls of the distended ovisac, compressed by the tunicaalbuginea and surrounding stroma, are thrown into delicate folds,fig. 560: the blood-clot which may have remained after theescape of the ovum is progressively absorbed. The plicatedovisac then contracts upon the cavity, and by the time the suc- 1 CCLIII .
. On the anatomy of vertebrates [electronic resource] . uptured orifice, fig. 566, b, b. In theCow and Sheep such altered i Graafian follicle assumes a brick-red colour; in the Sow a yellowish brown; and in the Womanthe brighter colour led to its being called a i corpus luteum. Inher the walls of the distended ovisac, compressed by the tunicaalbuginea and surrounding stroma, are thrown into delicate folds,fig. 560: the blood-clot which may have remained after theescape of the ovum is progressively absorbed. The plicatedovisac then contracts upon the cavity, and by the time the suc- 1 CCLIII . CCLIV . CCLV . 2 In cccvni. the diameter of the mature ovarian ovum is given, as being, in mand°g Too cat rko rabbit rat mouse pig cow 5f0-, guinea-pig of an inch. IMPREGNATION OF MAMMALIA. 71,3 ceeding ovisac with the ripening ovum has begun to protrudefrom the surface of the ovary, the old ovisac has lost its yellowcolour, with much of its size, and has retired inward. This move-ment, with the collapse of the wall, depresses the cicatrix of the 560. Corpus luteum, after escape of ovum, Human, ccxlv: aperture; and by these successive shrinkings and cicatrisationsof the burst ovisacs, the ovary becomes marked by pits and fur-rows in advanced life. If the expelled ovum be not impregnated,the changes of the ovisac into the yellow convolute cavity, theninto a small white stellate body, may occupy two months in theHuman subject; but, if the maturation of successional ova bedelayed by impregnation and its consequences, the first changegoes on to a greater degree, and the £ corpus luteum is not obliter-ated in less time than from thirteen to fourteen months : theinner coat, or original ovisac, is more thickened by a larger de-posit of yellow oil-granules;it becomes more deeply pli-cated, is then compacted intoa yellowish mass, and gains anadventitious white lining mem-brane, fig. 561. Rarely untilafter full gestation and deli-very is the cavity obliterated :it is then represented b
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