Archive image from page 629 of The cyclopædia of anatomy and. The cyclopædia of anatomy and physiology cyclopdiaofana05todd Year: 1859 55 UTERUS AND ITS APPENDAGES. First Stage. Origin of the Graafian Follicle. —The time of the first appearance of the fol- licle within the ovary is subject to considerable variation in the different orders of Mammalia. In all it occurs at a much later period than the first appearance of the seminiferous tubes in the male. Bischoff', who has devoted much attention to the examination of the follicle in its earliest stages of formation, has never been able to dis
Archive image from page 629 of The cyclopædia of anatomy and. The cyclopædia of anatomy and physiology cyclopdiaofana05todd Year: 1859 55 UTERUS AND ITS APPENDAGES. First Stage. Origin of the Graafian Follicle. —The time of the first appearance of the fol- licle within the ovary is subject to considerable variation in the different orders of Mammalia. In all it occurs at a much later period than the first appearance of the seminiferous tubes in the male. Bischoff', who has devoted much attention to the examination of the follicle in its earliest stages of formation, has never been able to discover the least trace of it in the dog and rabbit before birth. This is also the case in most instances in the human embryo, although examples occur of the ovarian fol- licles being already formed in the new-born Fig. 377. Represents the mode of formation of the Graafian follicle. (After Backoff.) A, portion of ovary of a fetal clog. The Graafian follicles are seen in the first stage of formation, consisting of little groups of primary cells in the midst of a tissue of similar structure. B, Portion of ovary of a dog four weeks old ; a de- licate fibrous coat now surrounds the groups of nucleated cells. c, Portion of ovary of a pig three weeks old. The follicle is here composed of transparent membrane, the outer surface of which, in the larger ones, is become fibrous. Its inner surface is lined by an epithelium of pale cells (membrana granulosa); within this is the germinal vesicle, surrounded bv granules resembling yelk granules. These contents are seen dispersed from a ruptured follicle at g. infant, and in advanced embryos. At first nothing is distinguishable in the ovary except a uniform mass of primary cells and cell nuclei. When the follicle or ovisac is about to form, there may be perceived little round or ovoidal aggregations of primary cells, forming groups which are distributed in considerable numbers through the ovary. These, from the circum- stance that the su
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