REGENERATION OF HYPOTHALAMIC NERVE FIBRES AFTER HYPOPHYSECTOMY IN THE GOAT

Abstract

ABSTRACT In goats kept for several months after hypophysectomy it was found that the nerve fibres of the hypothalamo-neurohypophysial tract had regenerated. A posterior lobe-like organ had formed in the neural tissue of the median eminence just proximal to the site where the nerve tract had been severed when the pituitary gland was removed. This new, small, ectopic infundibular process was not only well innervated but also highly vascularised and it contained large amounts of neurosecretory material. Some of the regenerating nerve fibres had grown out from the nerve tract into pars tuberalis and the meninges; many of these nerve fibres carried neurosecretory material. In one goat, not hypophysectomized but with a traumatic lesion of the nerve tract in the pituitary stalk, regenerating nerve fibres had also grown down across the scar of the lesion to reinnervate the degenerate distal part of the nerve tract. Within the hypothalamus the loss of nerve cells was consistently greater in the supraoptic than in the paraventricular nuclei.