THE FEiMALE REPRODUCTIVE ORGANS 



II 



After a certain time, which varies according to the species and 

 the occurrence of lactation and pregnancy, the corpus luteum 

 retrogresses and finally is either reabsorbed entirely or dwindles 

 to a small corpus albicans. 



The interstitial tissue of the ovary. The whole question of the 

 presence, formation and function of the so-called interstitial 

 tissue of the ovary is controversial. Clumps of large epithelial 



^ v.o. 



Fig. 6. — Ovary of Rabbit. 

 i.t. interstitial tissue; y.o. young oocjrtes. 



cells, presenting the appearance of secretory tissue, are very 

 obvious in the ovaries of such mammals as the rabbit, but appear 

 to be absent in others such as the mouse. Schaeffer (545), Aime 

 (3), Fraenkel (210), and O'Donoghue (480) give lists of species 

 showing the presence or absence of interstitial cells. According 

 to Bouin and Ancel (77) they are not found in the ovaries of 

 animals which ovulate spontaneously. The confusion as to the 

 distribution of this tissue is accentuated by the lack of any 

 unanimous definition. Some workers describe only obviously 

 extrafollicular tissue as interstitial, while others, maintaining 

 that interstitial cells are of follicular origin, apply the term to the 



