Evidence for a Specific Seminiferous Tubular Factor Affecting Follicle-Stimulating Hormone Secretion in Man

Abstract

A B S T R A C T The interaction of the testis and gonadotropin secretion was studied in 15 men surviving chemotherapy for lymphoma. Azoospermia and complete destruction of all testicular germinal elements were present in 10 of the 15 men; however, Sertoli cells and Leydig cells were present. In these 10 men plasma follicle-stimulating hormone (FSH) levels were fourfold higher than in normal men of similar age whereas luteinizing hormone (LH) levels were normal. In contrast, both FSH and LH were normal in the remaining five men. Three had a full complement of spermatogenic tissue on biopsy and normal sperm concentrations. The other two men were azoospermic; one demonstrated full spermatogenesis in 30% of his tubules; the other had only a few spermatogonia in all tubules. In those patients with lower levels of gonadotropins pituitary insufficiency was excluded by the demonstration of appropriate responsiveness of FSH and LH to clomiphene administration. Similarly, Leydig cell function was normal since plasma testosterone was within the normal range in 13 of the 15 men and only slightly decreased in two. Thus, following chemotherapy, testicular damage was restricted to the germinal tissue, and this in turn was associated with a selective increase in FSH. The source of the FSH inhibitor is either the Sertoli cell or early germinal elements. However, since FSH levels are only half as high as those reported for castrate men, other testicular factors may modify FSH secretion.

Hormonal characteristics of the human menstrual cycle throughout reproductive life.

“…There are no sexually unique hormones, although there are wide variations in the secretion of hormones related to reproduction. Evidence for inhibin in the male is accumulating (29)(30)(31)(32), and it has been invoked to account for high levels of FSH and normal levels of LH in oligospermic males (33)(34)(35), after testicular irradiation and after cvtotoxic chemotherapy (36,37).…”

Recovery of suppressed male reproduction in mice exposed to progesterone during embryonic development by testosterone

“…The increase in serum FSH levels could be due to the impairment of spermatogenesis in the spermatogenic compartment in the progesterone-exposed mice or through the inhibition of testosterone production. Thus, the increase in the levels serum FSH reflected the germ cell loss in the spermatogenic compartment or damage to the Sertoli cells, thereby affecting the feedback regulation of FSH secretion (van Thiel et al 1972). The increased levels of LH together with decreased levels of serum testosterone are indicative of decreased steroidogenic ability of the testes of the mice transplacentally exposed to progesterone.…”

Secretions of the Testis and Epididymis

“…This activity may be a lead in the long search for the substance 'inhibin', which was postulated many years ago to explain the rises in pituitary, urine and plasma FSH after selective destruction of the germinal epithelium (Mottram & Cramer, 1923;McCullagh, 1932;Johnsen, 1964;Van Thiel, Sherins, Myers & DeVita, 1972). Inhibin is thought to be produced by the germinal epithelium in proportion to the rate of sperm production and to act as a negative feed-back on the pituitary production and/or secretion of FSH.…”