Fig. 2

Influence of environmental and lifestyle factors throughout a man’s life. Numerous environmental or lifestyle factors can affect testicular development and function during both fetal life and adulthood. Exposure to these factors via the mother during pregnancy can affect the differentiation and/or endocrine functions of the fetal testis resulting in a reduced synthesis of androgens by Leydig cells and/or reduction in the final number of Sertoli cells. This can lead to an irreversible reduction in sperm count and sperm fertilizing capacities in adulthood. In adult men, the effects of environmental or lifestyle factors can affect spermatogenesis and/or the production and action of androgens. However, the impact is likely to be reversible because a new cycle of spermatogenesis is taking place approximatively every 74 days