494 



THE BRIDGE OF LIFE 



SPERMATOGENESIS -(in animals)- OOGENESIS 



Primary Primary 



spermatocyte oocyte 



I After duplication of ) 

 v chromonemata / 



Mctaphase of first 

 division of meiosis 



( Note tetrads ) 



Secondary 

 spermatocytes 



Metaphase of second WxM 

 division of meiosis 



(Note dyads ) 



Second 

 polar 

 bodies 



Secondary 

 oocyte 



From Genetics, Winchester, Houghton Mifflin 



Fig. 31.3. Spermatogenesis and Oogenesis. These diagrams show the similarities and 

 differences in the formation of sperms and eggs. For clarity of detail only six chromo- 

 somes are shown, although the human diploid number is actually 48. 



