[Reaction of rat fetal adrenals to stress exposure under encephalectomy]

The concentration of corticosterone in the suprarenals after the stress effect (injection of formol) was studied in 20.5 days old foetuses of the adrenalectomized rats, using the method of competitive binding. The concentration of corticosterone in the suprarenals of normal foetuses increased reliably within 30 min after the injection of formol; this reaction was absent in the encephalectomized foetuses. The results obtained suggest the participation of embryonic hypothalamus in the organization of stress response during prenatal development of rats.