A manual of midwifery / by Alfred Lewis Galabin.

  • Galabin, Alfred Lewis, 1843-1913.
Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: A manual of midwifery / by Alfred Lewis Galabin. Source: Wellcome Collection.

    61/912 (page 31)
    which is eventually converted into a fibrons cicatrix. It may well be that the ovule, itself an epithelial cell by origin, influences the cells around it while present in the follicle, causing them to prolife- rate into cells which behave like epithelium for the time, but, after the ovum has escaped, proceed to form connective tissue. From the mode of origin of the ovary, it follows that it is not covered by the peritoneum in the same sense as the other viscera. The superficial layer of the original germ epithelium is not de- veloped into ovules, but becomes the epithelial covering of the ovary (h, Fig. 19, p. 30 ; e, Fig. 20, p. 32). It is continuous with the peritoneal epithelium, but it is prismatic, and not flattened. The outer fibrous covering of the ovary, the so-called tunica albuginea, is simply a superficial condensed portion of the fibrous stroma of the organ. It derives its name from its whitish colour, due to its vascularity being less than that of the interior of the organ. Like the rest of the stroma, it contains involuntary muscular fibres, as well as connective tissue. All the ovules which are to be developed in the ovary exist in it at birth, and a far greater number are present than are required for ovulation throughout the whole period of active sexual life. The number at birth has been estimated as high as 35,000. A considerable proportion, however, appears to become atrophied, and disappear, so that in adult life, and even at puberty, the number is much smaller. Structure of the Ovary.—The ovary is generally described as made up of two portions—a cortical zone, containing the Graafian follicles, and an internal portion, consisting of the fibro-vascular stroma. This distinction, however, exists only in infancy and early childhood, and ceases to be marked before puberty, although the follicles are always chiefly situated near the surface. The stroma is made up of wavy connective tissue, mingled with elastic fibres, and also a considerable quantity of involuntary muscular fibres. To the action of the latter considerable importance is attached by some autho- rities, as influencing the rupture of the follicles and the expulsion of the ova. On section of an ovary after puberty, a few follicles are seen which have reached sizes varying from UP to -\ inch, but the great majority are visible only on microscopic examination. From the. section of a cat's ovary (Fig. 20, p. 32) it will be seen that the smallest follicles lie close to the surface. As they get some- what larger, they lie deeper in the ovary, but, as they approach maturation, their superficial part again approaches the surface until the covering gives way (see Fig. 21, p. 32). The explanation is that, the. superficial layer of the ovary being denser than the subjacent stroma (see fig. 20), tin: enlarging follicle at first goes inward in the direction of least resistance. When it has got so large that it