Age related Pituitary Tumor and Mammary Tumor, furthermore toxicity of Corticosteroids on lymphoid tissues in six months study in dogs. The above information will good line for comparison between incidence of Spontaneous Pituitary Tumor in Ageing Rats in comparison to Pituitary Tumor in human. Also the important of Corticosteroids in human the above study will show the side effect of corticosteroids.