47i THE OVAEIES. 



absent from the succeeding stratum of the stroma, but some^Yhat larger 

 cavities of the same kind, distended with fluid and containing ova, are 

 observed in smaller numbers embedded in the ovarian stroma for a 

 certain distance from the surface, but not extending to the deepest part 

 or that near the hilus. Of this second set of Graafian follicles, the 

 deepest are usually of the largest size, or most advanced. 



Further, in the ovaries of females who are approaching the period of 

 puberty, and during the whole of the child-bearing period of life, there 

 may be seen towards the surface, or even more or less projecting upon 

 it, a few larger follicles of various sizes, from a twentieth to a sixth 

 of an inch, which are the Graafian follicles with ova approaching or 

 arrived at a state of maturity. The more advanced of these seem to 

 have made their way from the deeper part by the absorption or at the 

 expense of the ovarian substance between them and the surface. They 

 still remain covered at the most projecting part by a thin layer of the 

 fibrous stroma and the epithelium. The smaller blood-vessels running 

 round the follicle from below, and minutely subdivided on its inner 

 surface, converge towards a point near the middle of the most project- 

 ing part, called the stigma. This marks the spot where the rupture of 

 the vesicle ultimately occurs, when at the time of full maturation the 

 vesicle opens, and its ovum and other contents escaping pass into the 

 open extremity of the Fallopian tube. This rupture of a Graafian 

 vesicle, or it .may be of more than one, occurs in healthy females at 

 every successive menstrual period. After the discharge of its contents, 

 the Graafian follicle is rapidly filled with a peculiar reddish-yellow mass 

 of granular elongated cells, which are rapidly developed in its interior, 

 constituting the first stage of formation of the body termed corjms 

 hitenm. When pregnancy occurs, this body enlarges, and becoming more 

 solid, advances to a fuller stage of development, which is maintained 

 during the greater part of the time of utero-gestation. But in the un- 

 impregnated female the corpus luteum begins to retrograde within 

 ten or twelve days after its commencement, and afterwards rapidly 

 shrinks and ultimately disappears. It thus happens that, without preg- 

 nancy, the ovaries may naturally present during the whole of the child- 

 bearing period of life the corpora lutea of menstruation, or their 

 vestiges, in various stages of advance or decline. 



The Graafian follicles in the ovary of middle life are to be found 

 in very various stages of development. 1st. By far the most 

 numerous and the smallest lie in the cortical layer already described. 

 The size of these is remarkably uniform, the largest scarcely passing 

 •j-Iq of an inch. These exist from an early period of foetal life, and are 

 in such numbers that it is estimated with gi'cat certainty that the 

 ovaries of a female child at birth do not contain less than 70,000 

 follicles, each one of which contains an ovum. 2nd. In the deeper 

 stratum of the ovary is found a succession of follicles in very much 

 smaller numbers, and of very various sizes from -jI-q to -^\, or even 

 ttV of an inch. And ord. There are the larger and fewer follicles ad- 

 vancing to and projecting on the surface. 



The more advanced Graafian follicles appear to have a very consistent 

 wall formed of the ovarian stroma ; but it is doubtful whether the 

 two coverings which have been described as belonging to them 

 deserve to be regarded structurally as distinct envelopes. Two layers 

 of condensed tissue may indeed be seen surrounding the cavity of the 



