The effect of testicular hormone on normal sexually mature rats. A method of biological assay

Abstract

The changes produced by injections of a purified preparation of testicular hormone extracted from urine were studied on 37 normal adult male rats belonging to 9 litters. The physiological variations from the average of the weights of the organs investigated were small. Therefore, by comparing the mean of the average changes in the litters and following exactly the technique and precautions given in the previous papers, the method described could be applied to normal rats for the study of physiological or pathological conditions or for the assay of substances which influence the weight of one or more organs. The effect of injections of the testicular preparation on adult rats was small, as judged by changes in the weight of the organs and the histological examination of the testes, differing in this respect from the quite definite effect on some of the organs of young rats, since only the large dose of 10 R.U. seemed to have a slightly depressing effect on the weight of the testes and the Leydig''s cells. Acceleration in the rate of retrogression of the thymus was noticed in all the rats injected with 1 and 10 R.U. The increase in the weight of the kidneys was very small, being present in most of the groups injected with the large dose.