THE MALE 



33 



Primordiol germ cell - 2N 

 @1 



SPERMATOGENESIS 



(@)@(@)@(®)@(@)(@) 



Primary oocyte {2N) 



(Mitotic=Equationcl 



division) 



First polar body 

 (Meiotic •Reductionol 

 division) 



®N-Secondary spermatocyte (2N 

 / (Meiotic = Reductional division) 



d) j-Spermatid (N) 

 (Metamorphosis) 



Spermatozoon (N) 



Frog's egg remains at metoptiase 

 of second maturation division until 

 it IS fertilized or dies 



The maturation process. Schematized drawings. The post-reductional division 

 is shown. In many forms the first division is reductional and the second is 

 equational. The end result is the haploid gamete, in either instance. 



matic reticulum. Both the cytoplasm and the nucleus grow and the 

 chromatic granules become finely divided and arranged into contigu- 

 ous rows, bound by an achromatic thread, together known as chromo- 

 somes. This is the leptotene stage of spermatogenesis. Shortly the 

 chromosomes become arranged in pairs which converge toward that 

 side of the nucleus where the centrosome is found. The opposite ends 

 of the paired chromosomes merge into the general reticulum. This 

 is the synaptene stage. The chromatin granules become telescoped 

 together on the filaments so that the aggregated granules, known as 

 chromosomes, appear much shorter and thicker. Pairs of chromo- 

 somes become intertwined and the loose terminal ends become coiled 

 and tangled together. This is the contraction or synizesis stage. Then 

 the members of the various pairs become laterally (parabiotically) 

 fused. While there is no actual reduction in total chromatin, there 

 is a temporary and an apparent (but not real) reduction in the total 

 number of chromosomes to the haploid condition, because of this fu- 

 sion. There is no actual reduction in the total amount of chromatin 



