GERM-CELL CYCLE IN ANIMALS 



of chromosomes and the amount of chromatin in 

 the germ cells. Typically, both male and female 

 germ cells divide twice during the process of matura- 



PRIMORDIAL 

 GERM-CELL 



SPFRMATOGONIA,,-- 



MULTIPLICATION 

 PERIOD 



SPERMATOZOA 



PRIMORDIAL 

 GERM-CELL 



PRIMARY 

 OOCYTE 



SECONDARY 



OOCYTES 

 (OVARIAN EGG 

 AND POLAR BODY) 



MATURE EGG 



AND 



POLAR BODIES 



MULTIPLICATION 

 PERIOD 



MATURATION 

 PERIOD 



* 



FIG. 9. Diagrams illustrating (above) the stages of spermatogenesis 

 and (below) of oogenesis. The primordial germ cell is represented 

 as possessing four chromosomes. 



