Morphology of the mammotrophs and gonadotrophs in the anterior pituitary gland of rats with protein-calorie malnutrition.

Abstract

The structure of the anterior pituitary gland of rats with protein-calorie malnutrition was studied at the light and electron microscopic levels. Male Sprague-Dawley rats were fed a low-protein diet from 20 to 50 days of age. The hypophyses from these animals, along with those from age-matched controls, were then removed and fixed for light microscopic immunocytochemical analyses, using anti-rat PRL or anti-ovine LH beta serum, or for routine ultrastructural study. The overall number of mammotrophs and gonadotrophs appeared to be unaffected by the deficiency in dietary protein. However, the nuclei, in both cell types, were significantly smaller in the malnourished rats. Cytoplasmic volume was also apparently less than in control rats, leading to the "crowding" of adjacent cell types. Additionally, in the malnourished rats, the mammotrophs assumed a less polygonal profile, while the gonadotrophs, which were more irregularly shaped in the central zone, rarely displayed the negative image of a Golgi complex. Ultrastructurally, the mammotrophs in the experimental rats had a less extensively developed granular endoplasmic reticulum and Golgi complex. The number of secretary granules was not different; however, their size was markedly less and their shape was round to ovoid, rather than pleomorphic. Two types of gonadotrophs were distinguished, based on the classification of Kurosumi et al. ('76). The type-I cell (former "FSH" cell) had a smaller Golgi complex, less vesicular endoplasmic reticulum and smaller secretory granules. The major alteration in the type-II gonadotroph (former "LH" cell) was the smaller size of the secretory granules. The morphological changes found in this study support our previous physiological observations (Herbert, '80), which demonstrate that prolactin and gonadotrophin secretion are severely impaired in rats suffering from protein-calorie malnutrition.