A new male pseudohermaphrodite rat mutant with androgen deficiency

A male pseudohermaphrodite rat mutant showing a blind-ending vagina, small undescended testes, rudimentary male sex accessory organs and XY karyotype was investigated. Genetic analysis revealed an autosomal single recessive transmission of this defect and indicated that the gene action is restricted to males. Microscopic examination showed an absence of typical Leydig cells in testes of the mutant. Plasma concentrations of testosterone were extremely low and the values were comparable to those of castrated male rats and did not change after castration and/or after administration of hCG. Plasma concentrations of LH and FSH were remarkably high and the values were comparable to those of long-term castrated normal male rats which declined to basal levels after administration of exogenous testosterone. Weights of thymus and adrenal glands decreased and weights of preputial glands, kidneys and male accessory sex organs increased in response to exogenous testosterone. These results indicate that the primary defect in the mutant is an androgen deficiency probably due to a Leydig cell agenesis in the testes.