CHAP, i.] FEMALE ORGANS. 1493 



gated in a zone, lying beneath the superficial epithelium of the 

 free surface of the ovary, but separated from it by a layer of stroma, 

 the tunica albuginea; this ' cortical layer/ or 'germinal zone/ corre- 

 sponds to the germinal layer spoken of above. The larger follicles 

 are distributed throughout the thickness of the ovary, but are 

 absent from the hilus and from a wedge-shaped strand of stroma, 

 which at the hilus passes from the broad ligament into the ovary. 



In this strand the connective tissue is for the most part 

 ordinary connective tissue, made up of the usual fibrillated bundles, 

 and carries the blood vessels passing to the ovary from the broad 

 ligament. Some plain muscular fibres are present among the con- 

 nective tissue bundles ; and here and there in this situation are seen 

 in sections of the ovary tubes cut in various planes and lined with 

 short cubical or flat cells; these are parts of the "parovarium" 

 derived from the Wolffian body. Elsewhere, between and among 

 the follicles and in the tunica albuginea, the connective tissue has 

 peculiar characters ; it consists entirely of spindle-shaped nucleated 

 cells interwoven together ; these have a superficial resemblance to 

 plain muscular fibres, but are true connective tissue elements; 

 they are also present to a certain extent in the strand just 

 mentioned. 



930. In a Graaffian follicle which is large but not yet fully 

 developed and mature, one may recognize the following parts. 

 On the outside the follicle is defined by an envelope, theca, of 

 stroma, with its spindle-shaped cells and blood vessels. This is 

 limited internally by a delicate structureless membrane, the mem- 

 brana propria, and within this lies an epithelium consisting of two 

 or more layers of cells constituting the membrana granulosa; the 

 cells next to the membrana propria are columnar, the rest are 

 cubical or spheroidal. At one part the membrana granulosa 

 expands into a rounded mass of cells, bulging inwards towards 

 the centre of the follicle ; and in the midst of this mass of cells, 

 called the cumulus or discus proligerus, lies the highly developed 

 cell which is the ovum. The outline of the ovum is defined by an 

 investing membrane, which if the follicle be old enough has a 

 distinct double contour and is called the zona pellucida or, because 

 it is marked by radiating lines or striae, zona radiata; the cells 

 of the cumulus touching this are columnar in shape, and arranged 

 in a radiate manner. Within this membrane lies the cell body of 

 the ovum, which in the larger follicles has become granular by the 

 formation of yolk or vitellus. Placed, more or less excentrically, in 

 the cell substance is a large transparent spherical nucleus, the 

 germinal vesicle, in which may be distinguished a nuclear mem- 

 brane, a nuclear network with more fluid nuclear contents, and 

 either one or more than one conspicuous nucleolus or germinal 

 spot. 



If the follicle be one well advanced in development, a con- 

 siderable portion of its interior will be occupied by fluid, into 



952 



