Binding of human chorionic gonadotrophin to testicular biopsy tissue from infertile men and the effect of prior treatment with human chorionic gonadotrophin.

The binding of 125I-labelled human chorionic gonadotrophin (HCG) to testicular tissue obtained by biopsy from 27 infertile men has been investigated. Fresh tissue cut into pieces was used for these studies as homogenization and/or freezing severely reduced the ability of testicular tissue to bind HCG. In five infertile men who had a normal endocrine profile and normal testicular histology, 10.3 +/- 1.4 (S.D.) pg 125I-labelled HCG were bound/mg testis, which was similar to binding (7.9 +/- 3.6 pg/mg) to testicular tissue obtained from three apparently normal men who underwent orchidectomy for prostatic carcinoma. However, in five infertile men with germ cell aplasia binding was increased to 16.6 +/- 5.7 pg/mg tissue. Fourteen infertile men were injected 24 h before biopsy with HCG, and this treatment consistently, and in most cases significantly, reduced the testicular binding of 125I-labelled HCG compared with that found in untreated, infertile men. It was concluded that measurement of HCG-binding in testicular biopsy specimens is feasible and may prove useful in assessing similarities between Leydig cell function in man and animals.