44 



THE FOUNDATION 



Part I 



Distribution of chromosomes in the developmeni of 

 sperm cells. Dork chromosomes = mole inheritance. 

 Light chromosomes = femole inheritance. 



Body cell of fother 

 I.e. skin, muscle, etc 



Germ cell destined to divide 

 and develop into sperm cells 



Spermatogonium 



Primary — 

 spermatocyte 



A.B.MEIOTIC 

 divisions 



Secondary 

 spermatocyte 



MITOTIC 

 divisions 



Cell enlarges 



Similar chromosomes pair 



(Synapsis) 



Eacn chromosome duplicates 

 itself. Tetrads result. Tetrads 

 separate into pairs. Cell divides. 



MEIOSIS 



Tetrads separate into pairs. 

 Cell divides 



— Sister chromosomes 

 separate. 



Spermatids 



Sperm 

 cells 



Fig. 3.10. Diagrams showing the behavior of the chromosomes during (A) the 

 development of the sperm cell (spermatogenesis) and (B) the similar features in 

 the development of the egg cell (oogenesis). In each sex cell the process includes: 



