THE OVARIES GRAAFIAN VESICLES. 



989 



stroma, the fibres of which, although forming a felted tissue, have, with 

 the blood-vessels, principally a radiating direction from the lulus to the rest 

 of the surface. It contains numerous spindle -shaped cells, and also, ac- 

 cording to some writers, uustriped muscular tissue. Towards the surface, 

 the ovarian tissue, which in this part has been distinguished as cortical, pre- 

 sents, especially in children, a different appearance from the deeper or 

 medullary part, from being granular, and having within it great numbers of 

 small vesicles, the Graafian vesicles or follicles, which are absent from the 

 deep part. After the period of puberty, a certain number of the Graafian 

 vesicles, varying from twelve to thirty or more, have attained a larger size, 

 some having a diameter of from -j g th to ^th of an inch, or even more. 

 The great majority however, remain much smaller : thus Henle estimated 

 the number of vesicles of about ^ to -g^th ^ au * nc k * n diameter, in the 

 two ovaries of a girl of eighteen, at 72,000 (Syst. Anat., II. 483). 



The vesicles of DQ Graaf, when dilated, are filled in part with a clear, 

 colourless, albuminous fluid, the larger ones approaching the surface of the 

 ovary, on which they may sometimes be distinguished as semi-transparent 

 elevations. Each of these vesicles includes, besides its fluid contents, the 

 ovum a small round vesicular body, imbedded in a layer of cellular sub- 

 stance. Sometimes, though rarely, two ova have been found iu one vesicle. 



Fig. 688. 



Fig. 688. VIEW OP A PORTION OP THE SECTION OF THE PREPARED CAT'S OVARY, 



REPRESENTED IN THE PRECEDING FIGURE, MORE HIGHLY MAGNIFIED (from SchlOu). 



1, outer covering of the ovary ; 2, fibrous stroma ; 3, cortical layer of granular sub- 

 stance towards the surface ; 3', deeper parts of the granular substance ; 4, blood- 

 vessels ; 5, ovigerms forming a layer near the surface ; b', one or two of the ovigerms 

 sinking a little deeper and beginning to enlarge ; 7, one of the ovigerms farther developed, 

 DOW enclosed by a prolongation of the fibrous stroina, and consisting of a small Graafian 

 follicle, within which is situated the ovum covered by the cells of the discus proligerus ; 

 8, a follicle farther advanced ; 8', another which is irregularly compressed ; 9, the greater 

 part of the largest follicle, in which the following indications are given ; a, epithelial or 

 cellular lining of the follicle constituting the mernbrana granulosa ; b, the portion reflected 

 over the ovum named discus proligerus ; c, vitellus or yelk part of the ovum surrounded 

 by a vesicular membrane, which becomes afterwards the zona pellucida ; d, germinal 

 vesicle ; e, germinal spot or nucleus. 



