OVARIAN ATRESIA AND PARTHENOGENESIS 43 



for follicles indicates that the total number of atretic mature 

 ova reach their maximum in early dioestrus shortly after 

 ovulation. This is doubtless due to the continued formation 



TABLE V 



The Degree of Atresia of Ovarian Follicles of the Mouse at Four 

 Stages of the Oestrus Cycle. (From Engle, 19276) 



of antrum-containing foUicles at a fairly high rate for a 

 short time after ovulation. 



We have seen that ovogenesis continues during preg- 

 nancy. Engle's data dem- 

 onstrate that the formation ^. 



30 



and atresia of full-grown ^^ 





ova also occurs during preg 

 nancy, for he observed an t.§ 

 appreciable number of c^gio 

 pseudomaturation spindles 

 in ovaries taken during the 

 first 43/2 days of pregnancy. 

 These data are summarized 

 in Table VI and Figure 14. 

 It is notable that both the 

 total amount of atresia and 

 the atresia of mature ova is 



ATRETIC FOLLICLES 



PSEUDO-MATURATION 

 >-... SPINDLES I ^--'' 



•---.i \-^ 



STAGE OF DEVELOPMENT 

 -Fig. 14. Showing the number of 

 , , , i ii • • 1 atretic folhcles and pseudomaturation 



less throughout this period spindles in the median ovary at four 

 than during the period of stages in early pregnancy in the mouse. 

 1 i J i J- • (From the American Journal of Anat- 



least destruction m non- ^^^^y^ 

 pregnant mice. Unfortu- 

 nately, Engle does not give the percentages of atresia during 

 early pregnancy. 



The presence of cycles of atresia and growth in animals 



