The endocrine control of spermatogenesis.

The hormonal regulation of spermatogenesis involves a complex interplay within the hypothalamo-pituitary-testicular axis, which commences before birth with male sexual development and continues through puberty and into adulthood. Hypothalamic gonadotrophin-releasing hormone drives these events by inducing pituitary gonadotrophin secretion, thereby stimulating testicular androgen secretion (providing virility) and spermatogenesis (providing fertility). Evidence from both animal models and man supports a need for both follicle-stimulating hormone and testosterone in achieving full spermatogenic potential, but a species difference in their relative roles exists. Clinical endocrine disorders can arise from a deficiency of hypothalamic gonadotrophin-releasing hormone and/or pituitary gonadotrophins, which results in hypogonadotrophic hypogonadism, featuring delayed/absent puberty and infertility. Physiologically-based and effective treatment with pulsatile gonadotrophin-releasing hormone or gonadotrophins can often restore fertility. Clinical conditions can also be caused by rare genetic disorders of the gonadotrophin molecules or the receptors for androgens and gonadotrophins, which result in a range of phenotypes (from male pseudohermaphroditism through to infertility); these disorders provide a unique insight into the physiology of sexual development and spermatogenesis.