Lectures on the comparative anatomy of the placenta : first series / delivered before the Royal College of Surgeons of England, June, 1875, by Wm. Turner.

  • William Turner
Date:
1876
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Licence: Public Domain Mark

Credit: Lectures on the comparative anatomy of the placenta : first series / delivered before the Royal College of Surgeons of England, June, 1875, by Wm. Turner. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Development of the F(etal Membranes. The observations on the structure and development of tlie ovary, which have been made during the last few years, more especially by Professors Pfluger' and Waldeyer' and by Dr Foulis', have satisfactorily demonstrated that the ova are derived from the corpuscles of the epithelial layer which inTests the surface of the ovary. By a process of involution accompanied by a great growth of the ovarian stroma, many of these corpuscles become imbedded in the substance of the ovary. The nucleus of a corpuscle swells out into a spherical germinal vesicle, and con- tains in its interior a nucleolus, or germinal spot. Around the nucleus the protoplasm of the cell-substance increases greatly in amount to form the yelk. The peripheral portion of this yelk-protoplasm then differentiates into a cell-wall—the zona pellucida, or vitelline membrane—which completes the develop- ment of the ovarian ovum. The vascular connective-tissue stroma of the ovary forms a capsule around each ovum, which constitutes the vascular capsule of the Graafian follicle. This capsule is lined at first by a single, but afterwards by more than one layer of cells, which form the cells of the membrana granu- losa, or so-called epithelium of the Graafian follicle. These cells were believed by Waldeyer to be derived from certain of the epithelial ceHs investing the -ovary, which had been included in the ovarian substance along with those which developed into ova. But Dr Foulis has pointed out that they are descended from the connective-tissue -corpuscles of the vascular stroma. The Graafian follicle enlarges by the multiplication of the cells of the membrana granulosa, and by the secretion of follicular fluid. In the course of time it bursts, and the ovum is extruded. Being received by the Fa,llopian tube it is conveyed into the cavity of the uterus. Should the ovum become fertilized by the penetration of spermatozoa through the zona pellucida, a remarkable series of ^ Die Eierstocke der Saugcthicre und des Mensclien. Leipzig, 1863. • Eierstock und Ei. Leipzig, 1870. 3 Abstract in Proc. Roy. Soc. Edmhurrih, 1871—75, and in extenso in Transactions of the same Society, 1876. T. 2
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