ECOLOGY AND BIOLOGY OF THE PACIFIC WALRUS 



179 



The ovaries of adult females are 5 to 8 cm long and 2 to 4 cm in diameter, 

 being essentially oval and smooth. Usually, a few translucent follicles are visible 

 beneath the tunic or bulging slightly above its regular surface (Fig. 112). In 

 longitudinal section, those follicles appear as fluid-filled vesicles, irregularly 

 distributed in the cortical layer, just beneath the tunic. They may occur singly or 

 in clumps of two to six, usually with one follicle in each clump larger than the 

 others. Ripe follicles usually are single. 



The corpus luteum of pregnancy during gestation generally makes up one- 

 third to one-half of the ovary, causing a substantial bulge. The corpus usually is 

 derived from a single follicle, but I recorded 17 of 123 (13.8%) that were 

 compound. Each of the compound corpora was made up of one central corpus of 

 pregnancy with one to three adjacent accessory corpora lutea. In each instance, 

 there was but one ovulation scar in the tunic over the central corpus. Separate 

 accessory corpora lutea in the same or the opposite ovary were identified in three 

 other instances (2.4%) in this series of 123 specimens. 



Age at Sexual Maturity 



Males 



In the testes of 10 newborn males, the seminiferous tubules were small (57-68 

 ixm in diameter) and were lined with Sertoli cells and type A spermatogonia; 

 most of the tubules had no apparent lumen. A few cells with darkly stained 



