Morphological changes induced in rats following prolonged exposure to stress.

Prolonged exposure of male C. S. F. rats to irregular signalled footshick from which they could escape for up to 71 days produced profound morphological changes. Retardation in growth, adrenal hypertrophy associated with an increase in the zona fasiculata a-nd zona reticularis, and changes in the microcirculation of the heart were observed. There was a significant degree of congestion and dilatation of the microcirculation which was most marked in large venules, collecting venules and veins. An increase in PAS +ve material marginated in the venous endothelium was observed also, together with a suggested increase in mast cells and presence of vacuoles in the intima-media of the coronary arterioles. No pathological changes were observed in the renal cortex and medulla or the gastric lining. The changes in the microcirculation of the heart are discussed in terms of an oedematous reaction and a histamine type leakage of the endothelial lining.