Does maternal stress induce abnormal descent of the testis in prepubertal rats?

To investigate whether prenatal maternal stress, considered to alter plasma testosterone concentration and induce a lack of testosterone surge in male rat fetuses, has any effect on the growth of the processus vaginalis and testicular descent in male offspring.

Pregnant rats were divided into two groups. In group 1, the rats were placed three times daily for 60 min each session in Plexiglas rat holders (13x6x8 cm) illuminated by two 150-W flood lights from day 14 to day 18 of gestation during the dark phase of the animals' light (12 h) and dark (12 h) cycle. In group 2, pregnant females were not handled and acted as controls. After birth, the anogenital distance of both the male and female rats was measured, and the length of the processus vaginalis was measured at 7 days of age in some rats. Thereafter, at 21, 24, 27 and 30 days of age, testicular descent was assessed in the remaining male rats.

In group 1, at 21, 24, 27 days of age, testicular descent was delayed in the stressed rats compared with the control rats. At 30 days of age, five of 36 stressed male offspring showed abnormal testicular descent; three testes were in the superficial inguinal position and two were above the scrotum. Both the anogenital distance and the length of the processus vaginalis were significantly less in the stressed male rats than in the controls.

Maternal stress induced a female-like anogenital distance in male rat fetuses, and caused delayed and abnormal descent of the testis, by inhibiting the growth of the processus vaginalis after birth. Prenatal stress may therefore be involved in the delay of testicular descent in neonatal rats by inducing a mild anti-androgenic effect in the fetus.