Hypertonic solutions induce hemorrhage in the anterior pituitary in mice

Acute and intense hemorrhage in the anterior lobe of the pituitary was observed in mice treated with hypertonic solutions. The onset of hemorrhage and the spontaneous recovery phase were studied with light and electron microscopes. Ten minutes after ip injection of 9% NaCl, 8% NaHCO3, 3 M glucose or 3 M sucrose at a dose of 0.03 ml/g B. W. there was selective bleeding in the anterior lobe of the pituitary. The maximum extent of hemorrhage was reached 12 h after the injection of hypertonic solution and lasted for approximately 3 days. Ontogenetic study indicated that no pituitary hemorrhage occurred in mice younger than 2 weeks of age. Hypophyseal cleft was found to be not merely a residual lumen but an active site providing for accumulation and digestion of blood cells which flowed out of the bleeding anterior pituitary. By the end of a week, the necrotic tissue in the center of the anterior pituitary was replaced by granulation tissue consisting of fibroblasts, macrophages, capillaries and a stack of excess basal lamina.