Male reproductive system ontogeny: Effects of perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin

In utero and lactational exposure of male rats to 2,3,7,8-tetra-chlorodibenzo-p-dioxin (TCDD) profoundly affects ontogeny of the reproductive system. Anogenital distance is reduced, testis descent is delayed, and testis, epididymis, and accessory sex organ weights are, educed throughout sexual development. In addition spermatogenesis is inhibited, sexual behavior is both demasculinized and feminized, and the regulation of luteinizing hormone (LH) secretion is feminized. The ED50 for these effects is approximately 0.16 mu g/kg when TCDD is given as a single maternal dose on Day 15 of pregnancy. The effects of TCDD on the male reproductive system described above appear to be due, in part, to perinatal reductions in plasma testosterone concentrations. TCDD and structurally related compounds may similarly affect ontogeny of the male reproductive system in a variety of other species.