"In vivo" effect of beef hypothalamic extracts on the cells of rat adenohypophysis.

Administration of crude and semipurified beef hypothalamic extracts to normal male rats resulted in a considerable degranulation of acidophil, thyrotropic and gonadotropic cells of the adenohypophysis. This effect was evidenced from 10 to 20 min after intracarotid injection of these extracts. At 60 min, the three groups of cells showed moderate hypertrophy, and the chromophobe cells also showed some degree of enlargement. By 90 min, acidophils were apparently normal, whereas thyrotrophs and gonadotrophs were partially degranulated and vacuolized. These effects coincided with a drop in pituitary FSH (follicle-stimulating hormone) and LH (luteinizing hormone), as evidenced by specific bioassays in animals injected with similar extracts. The control animals, whether sham-operated or injected with saline, vasopressin or brain cortical extracts, did not show any degranulation in the adenohypophyseal cells. This investigation demonstrated that the well-known effect of hypothalamic extracts on pituitary tropins can also be evidenced at a histological level.