Abstract
Adult male rats were treated with adrenocortico- tropin or cortisone, or subjected to stress at 4[degree]C. One control group received 0.5% phenol, and another was untreated. The percentage of pituitary basophile cells was calculated and the basophiles were examined for Crooke''s hyaline change. Animals receiving cortisone and those exposed to cold stress were found to have a significant increase in the percentage of pituitary basophiles. The ACTH and 0.5% phenol-treated animals failed to show this response. Crooke''s change was prominent in animals receiving ACTH or cortisone and was also seen in the cold stress group but not in either control. In the rat, the percentage of anterior pituitary basophiles and the presence of Crooke''s change cannot be correlated with increased or decreased demand for andogenous adrenocortico-tropin. The fact that basophilic granules and the hyaline masses of Crooke''s cells stain histochemically for glycoprotein makes it apparent that they are not ACTH. The absence of increased numbers of basophiles of Crooke''s change in human pituitaries following prolonged stress points to important species differences in the occurrence of these findings.