Some observations on the anterior pituitary of the domestic fowl with the aid of the electron microscope.

Abstract

AbstractLipid accumulations in the gonadotrophs of the pituitaries of aging and castrate fowl have been demonstrated. Secretory granules and mitochondria play no part in their formation. Some lipids, perhaps all, occupy the cavities of the ER. The ER is a highly variable organelle, appearing as spherical or irregularly shaped vesicles in gonadotrophs or as lamellae in acidophiles. The Golgi complex is typical of pituitary cells in general. There are no bodies in the enlarged cavities of the complex and convincing evidence for the origin of all secretory granules within the small vesicles of the complex is lacking. Many secretory granules appear to be without membranes and to lie free in the cytoplasmic matrix. Observations on the pituitaries of broody hens confirm earlier conclusions that the broody cells appear during the incubation period and that they are small cells with large nuclei and reduced cytoplasm. The study also confirms the accumulation of secretory granules in laying hens at one side of certain cells which are interpreted to be either LH or FSH producing basophiles. Thiouracil feeding brings about some unexpected granular accumulations in the ER vesicles of thyrotrophs of the fowl pituitary. The granules may fuse to form larger structures with concentric rings. Whether the effect is direct or indirect through the thyroid is uncertain, but thiouracil feeding and thyroidectomy produce similar effects upon the pituitary. The interpretation of these changes remains to be determined.