MORPHOMETRICAL CHANGES IN THE RAT THYMIC LYMPHOID-CELLS AFTER TREATMENT WITH 2 DIFFERENT DOSES OF ESTRADIOL BENZOATE

In the present study we have evaluated morphometrically the contributi on of thymocytes to the thymic involution induced by a single injectio n either of 100 mu g or 500 mu g of estradiol benzoate. Our results de monstrate that changes in the numbers of both cortical and medullary t hymocytes contribute to thymic involution although the importance of t he first is quantitatively higher. On the other hand, while cortical p yknosis and a decreased mitotic index could be important for explainin g the estrogen-dependent thymic changes, the release of lymphocytes fr om thymus seems to be the main factor inducing the thymic involution a s well as the lack of recovery observed at the end of the experimental period.