A textbook of obstetrics . ndcontains much more proto-plasm, or germ-yolk, thandeutoplasm, or food-yolk. Inits maturation, or preparationfor impregnation, the ovumshows a curious movement ofits nucleus (karyokinesis, amoving of the nucleus), whichapproaches the cell-periphery,arranges itself in two star-shaped figures (the amphiasterstage), and extrudes portionsof its substance as little glob-ules (polar globules) upon theovular surface. These globules then disappear and are lost. It issupposed that they contain, perhaps, the male substances, whichmight unite with the female portions of the ov
A textbook of obstetrics . ndcontains much more proto-plasm, or germ-yolk, thandeutoplasm, or food-yolk. Inits maturation, or preparationfor impregnation, the ovumshows a curious movement ofits nucleus (karyokinesis, amoving of the nucleus), whichapproaches the cell-periphery,arranges itself in two star-shaped figures (the amphiasterstage), and extrudes portionsof its substance as little glob-ules (polar globules) upon theovular surface. These globules then disappear and are lost. It issupposed that they contain, perhaps, the male substances, whichmight unite with the female portions of the ovum to produce animperfect being, as is done in certain hermaphroditic , it is presumed, takes this measure to prevent partheno-genesis, or the closest kind of inbreeding. A similar action maybe observed in the spermatozoon during its development. Afterthe extrusion of the polar globules the nucleus retreats into theinterior of the ovum and becomes the female pronucleus. Theovum is now ready for Si ifp K Fig- 53-—Section through part of amammalian ovary : KE, Germinal epitheli-um ; PS, an egg-cord ; i\ U, primitive ova ;G, investing cells; A*, germinal vesicle ;S, follicular cavity arising in one of theolder follicles ; Lf, follicular cavity, moreenlarged ; AY, nearly mature ovum, whichhas developed around it the zona pellu-cida, Mp; Mg, membrana granulosa; E>,Discus proligerus; So, ovarian stroma;Tf, capsule of follicle ; g,g, blood-vessels;u, immature Graafian follicle (after Wie-dersheim). OVULATION. 61 The Discharge of the Ovum from the Ovary and its Migra=tion to the Uterine Cavity.—Ova are discharged from the ovaryfrom puberty until the menopause,—that is to say, on the average,from the fourteenth to the forty-fifth year. Ovulation, however,
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectobstetrics, bookyear1
