A Quantitative Study of the Para Ventricular Nucleus and Its Alteration in Hypophysectomy

FROM THE EXTENSIVE retrograde change observed in the supraoptic nucleus after W hypophysial stalk resection (I, 2, 3) it appears that practically all of the fibers JL. from the supraoptic nucleus enter the neurohypophysis. While some cells of this nucleus remain intact after the usual hypophysectomy, these may be assumed to be connected with the median eminence of the tuber cinereum which is left intact and which is now regarded as part of the neurohypophysis (2–5). The relation of the paraventricular (filiform) nucleus to the innervation of the hypophysis is not so evident. Numerous authors have reported varying degrees of cell loss in this nucleus of various so-called hypophysectomized animals. Magoun and Ranson (3) in a study of 11 monkeys estimated that about 20 per cent of these atrophy as a result of severing the infundibular stem. Rasmussen (1) was not so sure that it occurred regularly in the rat.