TYPES OF (ESTROUS CYCLE 



6i 



cEstrous period. In pseudo-pregnancy, development continues 

 up to the fifth or sixth week, after which degeneration takes 

 place. 



In virgin ferrets, the mammary glands are entirely unde- 

 veloped both in ancestrus and oestrus. During pseudo-pregnancy 



Fig. 34. — Section of Mammary Gland of twenty-nine 



DAYS PREGNANT RaBBIT. 



c.t. connective tissue; I. a. lobules of alveoli. 



the ducts grow out round the nipple, and develop bud-like 

 terminations consisting of secretory alveoli. 



{g) PRIMATES 



The most obvious stage of the oestrous cycle in Primates is, of 

 course, the menstrual period, and most of the early work on the 

 Primate cycle was directed to analysing the significance of this 

 phenomenon. The correlation of the ovarian and uterine cycles 

 has been attempted systematically only during recent Vears. 

 Little success has been attained, and Heape's original observa- 



