Influence of rat hypothalamic extract on gonadotropic activity of cultivated anterior pituitary cells.

Two types of culture method, tissue explant culture and single cell culture, were employed in cultivation of the rat anterior pituitary. In the single cell culture, cells proved to maintain the histological features similar to the pituitary cells in vivo, indicating that this technique can be used for studying the function of the pituitary cells in vitro.The addition of the crude hypothalamic extract made from normal or castrated mature rats into the culture induced increases in gonadotropin contents of both culture fluid and cells. By the treatment of the culture cells with the extract, the cytoplasmic granules stained with Giemsa showed an increase in number and the reaction of the cells to PAS became positive. Neurohypophyseal hormones did not show the gonadotropin-increasing effect.It is thus concluded that the hypothalamic extract contains substance which is capable of stimulating directly the anterior pituitary cells to secrete gonadotropin. The nature of this active material remains obscure.