Testicular toxicity of methylmercury: analysis of cellular distribution pattern at different stages of the seminiferous epithelium.
Stage-specific distribution of methylmercury (MM) and spermatogenic changes were analyzed in rats administered 5 or 10 micrograms MM/kg, ip, daily for 15, 30, 60, and 90 days. MM deposition, as grain number/cm2 was noted in basal portions at later stages on day 15, which increased gradually by day 90. MM deposition was in the order of stages IV, VII, XIV, IX, being higher in adluminal portions on days 30 and 60. MM-enriched cytoplasmic masses leaked out through disintegrated tubular membrane on days 60 and 90. Epithelial damage, at stages late XIV through IV, V through VI, VII through VIII, XIII through mid-XIV, and IX through XII, accorded with the gradual deposition of MM. As profound cell death occurred between zygotenes to pachytenes and dividing spermatocytes to step 1 spermatids, the spermatids were conspicuously decreased at later times. It is possible that MM distorts the barrier system at stages IX through XII, gets distributed within the tubule, and hence may pose a direct or Sertoli cell mediated effect at stages XII through early XIV in a dose-duration-MM burden related manner.