Spermatogenesis.
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   Germ  cells  near  the  outer  wall of the seminiferous tubules of the
   testis differentiate into stem cells called spermatogonia.
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   Spermatogonia   divide   by   mitosis,   and   mature   into   primary
   spermatocytes.
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   Each primary spermatocyte undergoes meiosis:
<BR><LI> meiosis I yields 2 haploid secondary spermatocytes
<BR><LI> meiosis II yields 4 equal-sized spermatids.
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   The spermatids migrate toward the lumen (central opening).
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   Sertoli  cells  supply nutrients for the spermatids, which mature into
   motile sperm in the epididymis.
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   Review:  <A ClAsS=MID Href="../../../med/Vid/Johnson4e/Anim/ch30/spermatogenesis.swf" oNClick="popurlt('../../../../med/Vid/Johnson4e/Anim/ch30/spermatogenesis.swf');txtcolor('spermatogenesis2','gray');return false;" Id=spermatogenesis2><iMg sRc="/images/shockwave.gif" aLt='' boRDer=0></A>
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