[Development of the pituitary-adrenal axis during fetal life: modalities and regulation]

In mammals, the fetal adrenal gland plays a key role during late gestation since the maturation of the fetus and the adaptation of the neonate to extra uterine life mainly depend on glucocorticoids. We review herein the present knowledge concerning the modalities and the endocrine control of the development of the pituitary-adrenal axis in the two most studied models: the ovine and the human fetus. Although the anatomy of the adrenal gland is different in these 2 species, the mechanisms involved in the maturation of adrenocortical cells appear rather similar. Moreover, in both species, the prepartum rise of corticosteroid plasma levels which conveys growth and differentiation of adrenocortical cells, is under pituitary control; this likely involves an increase in the "corticotropic activity" which results from changes in the cleavage of POMC and possibly from a synergistic of inhibitory effect of other hormones with ACTH.