. Hand-book of physiology . ure they form little prominences on theexterior of the ovary covered only by the peritoneum. Eachfollicle is formed with an external membranous envelope com-posed of fine fibro-cellular tissue, and connected A\ith the sur-rounding stroma of the ovary by networks of blood-vessels(fig. 63^. This envelope or tunic is lined with a layer ofnucleated cells, forming a kind of epithelium or internal tunicand named mejnhxma granulosa. The cavity of the follicleis filled with an albuminous fluid in which microscopic gra-nules float; and it contains also the ovum or ovule. The
. Hand-book of physiology . ure they form little prominences on theexterior of the ovary covered only by the peritoneum. Eachfollicle is formed with an external membranous envelope com-posed of fine fibro-cellular tissue, and connected A\ith the sur-rounding stroma of the ovary by networks of blood-vessels(fig. 63^. This envelope or tunic is lined with a layer ofnucleated cells, forming a kind of epithelium or internal tunicand named mejnhxma granulosa. The cavity of the follicleis filled with an albuminous fluid in which microscopic gra-nules float; and it contains also the ovum or ovule. The ovumis a minute spherical body situated, in immature follicles, neartheir centre; but in those nearer matiu-ity, in contact Fiij. 63.* with the membrana granulosa,at that part of the folliclewhich forms a prominence onthe surface of the ovary. Thecells of the membrana granu-losa are at that point more nu-merous than elsewhere, and areheaped around the ovum, form-ing a kind of granular zone, the discus proligerus (fig. 63).. * Fig. 63. Section of the Graafian vesicle of a Mammal, after VonBaer. 1. Stroma of the ovary with blood-vessels. 2. and 4, Layers of the external coat of the Graafian vesicle. 5. jNIem-brana granulosa. 6. Fluid of the Graafian vesicle. 7. Granular zoneor discus proligerus, containing the ovum (8). G30 STRUCTURE OF THE UXIMPREGNATED OVUM. Ill order to examine an ovum, one of the Graafian vesicles,it matters not whether it be of small size or arrived at ma-turity, should be pricked, and the contained fluid received upona piece of glass The ovum then, being found in the midst ofthe fluid by means of a simple lens, may be further examinedwith higher microscopic powers. Owing to its globular form,however, its structure cannot be seen until it is subjected togentle pressure. The human ovum is extremely small, measuring, accordingto BischoiF, from -^^ to -j^-q of an inch. Its external investmentis a transparent membrane, about 0-5V0 ^^ ^^ inch in thi
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectphysiology, bookyear1
