CHANGES IN THE OVARY 



123 



case of the rabbit, concludes that the liquor folliculi is secreted by the 

 follicle-cells, without their undergoing destruction (or that.if this occur, 

 it is immaterial to the process of liquor formation), in the same way 

 as the urine is secreted by the epithelium of the renal tubules. In 

 support of this view Honore points out that there are no indications 

 of degeneration or destruction of the follicular epithelial cells of the 

 ripe follicles during oestrus, and moreover, that these cells are retained 

 in the follicle at the time of ovulation, giving rise subsequently to 



FIG. 36. Human ovum at termination of growth period. (After van der 

 Stricht.) Yolk granules, vacuoles, and fat drops are seen. 



the luteal cells of the corpus luteum. It would appear possible, 

 however, that the liquor folliculi is formed partly by the secretory 

 activity, and partly by destruction of the follicle-cells, just as, 

 according to one view, milk is derived from both the secretion and 

 the disintegration of the cells of the mammary gland (see p. 592). 1 



Heape 2 states that during the growth of the ovum nourishment 

 is supplied to it by the aid of the discus proligerus, for fine proto- 



1 For rate of growth in avian ova, see Eiddle (" Studies on the Physiology 

 of Reproduction in Birds," Amer. Jour, of Physiol., vol. xli., 1916). Riddle states 

 that yolk formation is not necessarily connected with the production of ova 

 (Bid. Bull., vol. xxii., 1912). 



2 Heape, "The Development of the Mole," Quar. Jour. Micr. Science, 

 vol. xxvi., 1886. 



