. The science and art of midwifery. partitions, with theincluded cells, are rudimentary Graafian follicles. Two distinct ova,within the same Graafian follicle, are of rare occurrence. As the ovaenlarge, and the epithelial cells multiply, an irritative action is set upin the surrounding stroma. An increase in vascularity results, and DEVELOPMENT OF THE OVUM. 37 young connective tissue is developed about each epithelial the follicle grows, the outer layer becomes fibrillated. Thus aroundeach Graafian follicle a distinct envelope is formed, termed by Baerthe theca folliculi, consist
. The science and art of midwifery. partitions, with theincluded cells, are rudimentary Graafian follicles. Two distinct ova,within the same Graafian follicle, are of rare occurrence. As the ovaenlarge, and the epithelial cells multiply, an irritative action is set upin the surrounding stroma. An increase in vascularity results, and DEVELOPMENT OF THE OVUM. 37 young connective tissue is developed about each epithelial the follicle grows, the outer layer becomes fibrillated. Thus aroundeach Graafian follicle a distinct envelope is formed, termed by Baerthe theca folliculi, consisting of an internal vascular coat, the tunicapropria, and an external fibrillated coat, the tunica fibrosa. Each primordial ovum is at first encircled by a single layer ofcylindrical cells. Gradually new layers form, in which the ovum liesimbedded. Afterward, at a point remote from the ovum, a crescent-shaped opening makes its appearance, which becomes filled with aclear fluid derived from transuded serum, and possibly in part from. Fig. 31.—Portion of vortical section through ovary of bitch, o, epithelium of ovary ; b, b,tubules of ovary ; c, young follicles ; d. mature follicles: e, discus proligerus, with ovum ;epithelium of second ovum in same follicle ; g, tunica fibrosa folliculi; h, tunica propriafolliculi; i, membrana granulosa. (Waldeyer.) disintegrated epithelium. A heap of cells remains about the ovum,and forms the discus proligerus. With the increase of the follicular 58 PHYSIOLOGY OF THE OVUM. fluid, the cylindrical cells are pressed against the membrana propria,and form a third coating, or layer, termed the membrana granulosa. A glance at a transverse section through the ovary of a maturemammal exhibits follicles of different ages. To recapitulate : The young follicles are composed of primordial ova, surrounded byepithelium, and imbedded in the ovarian stroma. The fully developed follicles possess a vesicular character. Theyare surrounded by a connective-tissue w
Size: 1448px × 1725px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookidsci, booksubjectobstetrics
