Cell Division in Relation to Reproduction - 53 



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A 

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S 

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SPERMATOCYTES 



IN TESTIS 



MITOTIC MULTIPLICATION 



MEIOSIS 



STARTING 



ANAPHASE 



2nd MEIOTIC DIVISION 



2nd MEIOTIC DIVISION 

 SPERMATIDS 



METAMORPHOSIS, NUCLEAR CONDENSATION 



MATURE SPERM 



Fig. 3-10. Diagram of meiosis as observed in a testis during the production of sperm. Note that the prophase 

 of the first meiotic division differs in several ways from the prophase of an ordinary mitotic division: (1) it en- 

 dures much longer; (2) it is accompanied by considerable cell growth; and (3) it involves synapsis between the 

 members of each homologous pair of chromosomes. Moreover, the second division is unique in that no replica- 

 tion of the chromosomes takes place and the interphase between the first and second divisions is exceptionally 

 short. Meiosis leads to the production of haploid cells (or nuclei) from diploid progenitors* whereas mitosis trans- 

 mits an unchanged number of chromosomes, either diploid or haploid, to the daughter cells (or nuclei). In 

 mitosis, moreover, the members of the homologous pairs, when pairs are present, do not associate as pairs. 



