Down-regulation of testicular follicle-stimulating hormone receptors by human menopausal gonadotropin in infertile men.

We measured testicular FSH receptors in 27 infertile men before, or 1, 3, 5, 7, or 14 days after a single administration of 150 IU of hMG. The administration of hMG reduced Bmax for FSH receptors to about 50% of that in the preadministration testes for 5 days. From the seventh day, Bmax of FSH receptors began to increase and returned to the preadministration level 14 days after the administration.