[Testicular follicle-stimulating hormone receptors in idiopathic male infertility].

To ascertain whether abnormalities in testicular binding of follicle-stimulating hormone (FSH) are related with spermatogenic impairment found in idiopathic male infertility, we measured FSH receptors in testicular tissues obtained by biopsy from 48 infertile men. The 48 infertile men were divided into 3 groups by histological grading using Johnsen's score count, and testicular FSH receptors among these groups were compared. Although 9 of the 18 infertile men with low Johnsen's score count and 5 of the 15 men with middle score count had no obvious FSH binding sites with high affinity, all 15 men with a high score count had high affinity FSH binding sites. In connection with high affinity binding sites for FSH, maximum binding number (Bmax) decreased significantly with the degree of spermatogenic impairment, but the association constant (Ka) was similar among the 3 groups. The present findings demonstrate that the decrease in testicular high affinity binding sites for FSH is related with the degree of spermatogenic impairment found in idiopathic male infertility.