MATURATION PHENOMENA 



213 



The Maturation Divisions. The maturation divisions in male 

 and female organisms, while similar so far as the chromatin is 

 concerned, do not result in the formation of the same number 



PRIMARY 

 SPERMATOCYTE 



SECONDARY 

 3PERMATOCYTE5 



PRIMORDIAL GERM-CELLS 



WITH DIPLOID NUMBER OF CHROMOSOMES X 

 N THIS DIAGRAM) 



MULTIPLICATION PERIOD 



MANY GENERATI 



SPCKMATO 



GROWTH PERIOD 

 5YNAPSIS 



UNION OF CHROMOSOMES IN PAIRS 



HAPLOio NUMBER) OF BIVALENTS 



BIVALENTS LONGITUDINALLY SPLIT 

 FIRST MATURATION DIVISION 



I SPLIT CHROMOSOMES 



MATURATION DIVISION 



SINGLE 

 CHROMOSOMM 



PRIMARY OOCYTE 

 (OVARIAN EGG) 



SECONDARY OOCYTES 



EGG 1" POLAR BODY 



POLAR BODY 



(w SOME CASES) DIVIDES 



-z- POLAR BODY 



FERTILIZATION 



FIR3T CLEAVAGE 



FIG. 90. Diagram of the maturation divisions of the male and female germ 

 cells. Four chromosomes are present in all cells of the body of the case illus- 

 trated. (The polar bodies are represented as much larger than they actually are 

 in relation to the egg cell.) 



of mature germ cells. From each primordial egg cell only one 

 mature egg is formed, while three rudimentary eggs called polar 

 bodies are formed, which have no part in development, but de- 

 generate and die. From each primordial cell of the spermato- 



