[Age of the father and development].

Testicular ageing affects at the same time the individual and his lineage. In the individual, vascular, endocrine, blood testis barrier and Sertoli cells changes because of age lead a decrease of spermatozoa number and an alteration in their form and motility. These changes lead a gradual decrease of fertility. In the progeny, paternal ageing is responsible for new dominant autosomic mutations which themselves cause different malformations, as achondroplasia, Apert or Recklinghausen disease, Marfan Syndrome etc. and perhaps for certain chromosome X linked recessive mutations as Duchenne myopathy or hemophily A. Moreover, in animal and man, paternal ageing seems responsible for a gradual lowering in the level of progeny cerebral functions. In man, very youthful age is also related to these effects. Thus, the curve corresponding to this phenomenon presents an inverted U-Shape, of which the top corresponds to about thirty years of paternal age. Maternal age does not appear to play a part in this event. On the whole, these results pose the problem of the optimum age for fatherhood.