Maternal chromosomes 



BODY (SOMATIC) CELL— T*^ 

 Paternal chromosomes ^^E</y 



PRIMORDIAL GERM CELL 



SPERMATOGONIUM 



SPERMATOGONIUM 



Growth 



PRIMARY SPERMATOCYTE 



Homologous chromosomes in synapsis 



Tetrad 



PRIMARY SPERMATOCYTE 



End view of tetrad 



First maturation 

 (reduction) division 



SECONDARY SPERMATOCYTE 



SPERMATID 



SPERMATID 



SPERM 

 CELL 



Figure 404. The chromosome cycle in man. Diagrams illustrating the distribution of chromo- 

 somes during spermatogenesis, oogenesis, fertilization, and early embryonic development. 1 he 

 primordial germ cells are represented as containing 4 chromosomes of two different lengths; one 

 of each length having been derived from the mother (maternal) and the other from the 

 father (paternal). All chromosomes in the zygote received from the sperm are thereafter 

 paternal, and those received from the mature egg are thereafter maternal, regardless of what they 



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