On serial histological sections of the testes, stained with hematoxylin-eosin, using a morphometric device, the total numbers of spermatogenic cells and sustentocytes (Sertoli cells) were measured in the convoluted seminiferous tubules of neonatal rat pups. Experimental groups consisted of rats born from females with experimental liver damage of various origins--autoimmune (n = 33), toxic (n = 32), alcoholic (n = 12), and medicinal (n = 27). The control group included pups born from normal female rats (n = 14). In experimental rats both increase and decrease of the total number of sustentocytes was detected. In the animals of most of the experimental groups, sustentocyte cell index reflecting the ratio of the number of spermatogenic cells and sustentocytes, was decreased.