The stress-induced activation of the corticostimulating function of the pituitary gland was noted to vary according to sex in both the adult and the newborn. The pituitary response in testosterone or estradiol-injected females at the time of birth was similar to that of intact males, in contrast, the castration of the males performed just before the postnatal surge of plasma testosterone was unable to modify at the 8th day, the male characteristic evolution in response to ether inhalation. Present data suggest--in the male, prenatal differentiation of the neuroendocrine pathways involved in the pattern of ACTH release in response to ether inhalation, probably in correlation with the peak of plasma testosterone on day 19 of gestation--in the female, the existence of androgen--sensitive structures in early postnatal life. An alpha stimulatory effect of norepinephrine on these neuroendocrine pathways was suggested. Present report also discuss--the catecholaminergic control of CRF X producing neurons--the sex dependent AVP and/or oxytocin (OT) release induced by a stress--the AVP and OT potentiation of CRF-induced ACTH release.