I04 FOLLICULAR DERIVATIVES IN VERTEBRATES 



III 



Pre ovulation corpus luteum 



Fig. 73. Modifications of the pre-ovulation corpus luteum. 



ized by an incomplete organization of the hypertrophying 

 granulosa tissue into a gland, whereby only the wall thickens 

 and a central cavity remains (Fig. 73a). 



^. In the corpus luteum solidum the entire space is organ- 

 ized into one solid gland. In contradistinction of the corpus 

 atreticum, this gland consists exclusively of granulosa-lutein 

 cells and differs from the post-ovulation corpus luteum only 

 in that the ovum disintegrates and that there is no rupture 

 (Fig. 73b). 



y. Pre-ovulation corpus luteum with retention of the 

 ovum is also a frequent occurrence. The granulosa tissue 

 hypertrophies around the ovum and forms a solid lutein 

 gland in which the egg cell is also destroyed, but not until 

 the regression phase sets in. In mammals it usually occurs 

 in corpora lutea which are of the same age as the post- 

 ovulation corpora lutea in which there has been no ovulation. 

 Such pre-ovulation corpora lutea, which have also been des- 

 cribed by Corner (1940) under the name of corpora lutea 

 aberrantia, and by COLE, HoWELL, and HaRT (1931) as 

 corpora lutea accessoria, have the same length of life as their 

 sisters, the post-ovulation corpora lutea, and are subject to 

 the same cyclic changes (Fig. 73c). 



d. The pre-ovulation corpus luteum ruptum is distin- 

 guished from the former by the oolysis and rupture occurring 

 already during the preliminary phase, in which the substance 



