[Features of the histogenesis of testicular yolk sac tumors in children].

32 cases of a yolk sac tumour of the testis in children aged up to 5 years underwent retrospective morphological study. Foci of proliferation of activated gonocytes identical to the type A spermatogonia with clear nuclei and the type B spermatogonia characterized by a negative PAS-reaction and reaction to alpha-fetoprotein are observed in the seminiferous tubules surrounding a tumour. Besides this areas of the primordial germinogen cell generation are found among the cells lining the system of labyrinths and channels of the yolk sac tumour. A new hypothesis of the yolk sac tumour histogenesis in the child testis is put forward--namely, through the transformation of the activated gonocytes in the seminiferous tubules into their "somatic" phase, i.e. into the yolk sac elements from which they originate. Likewise, the scheme is suggested reflecting a cyclic character of the germinogenic cells in ontogenesis. This scheme allows visual representation of the process of the parthenogenetic development of germinogenic tumours.