Sperm continuous production

The testis, like the ovary, has both gametogenic and endocrine functions. The onset of gametogenic function of the testes is controlled largely by the secretion of FSH by the pituitary. High concentrations of testosterone locally are also required for continuing sperm production in the seminiferous tubules. The Sertoli cells in the seminiferous tubules may be the source of the estradiol produced in the testes via aromatization of locally produced testosterone. With LH stimulation, testosterone is produced by the interstitial or Leydig cells found in the spaces between the seminiferous tubules. 

Adaptation by enzyme replacement is more important in nondividing cells than in a continuously growing population. In the latter case, a less appropriate enzyme complement can be diluted out by daughter cells containing enzymes more suitable for the new nutritional state. A limited life for the cells would also facilitate such adaptation. However, adaptation via the production of new cells is only relevant to those mammalian cell types where the cells are not physically confined to a discrete area or to those cells which have a short life span. Examples are sperm, erythrocytes, other blood cells, and gut mucosal cells. Yet these cells are typically highly specialized, of relatively constant composition, and rarely show adaptation. 

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