Pituitary-adrenal function after isolated removal of the median eminence in the rat.

Removal of the median eminence (ME) resulted in a 30-35 per cent reduction of the weight of the adrenals of female rats as compared to sham-operated controls. Hypophysectomy reduced the adrenal weight by 65-70 per cent during the same period of the time. The question arose as to whether the higher adrenal weight of the ME-ectomized animals reflected partially maintained hypothalamo-hypophyseal-adrenal function. a combined (either + blood withdrawal) stress did not cause significant increase in plasma corticosterone level in animals whose ME was removed 3 weeks earlier. However, 9 weeks following the removal of the ME, female rats responded to the stress. Possible regeneration of axons belonging to the parvicellular neurosecretory system is discussed.