HPG Axis: The Central Regulator of Spermatogenesis and Male Fertility

Pituitary gonadotropins have been established as essential components for the differentiation of the male reproductive organs. Human sexual maturation and spermatogenesis are intricately regulated by the hypothalamic-pituitary-gonadal (HPG) axis, which eventually determines the reproductive potential of an organism. Alterations affecting this fine balance can severely impair sexual development and fertility. These defects may result from mutations, small deletions or polymorphic changes within the regulatory genes involved in the biosynthesis of hormones, hormone receptors, growth factors and their associated signal transduction pathways. This present chapter summarizes the functioning and regulation of the HPG axis, its control over spermatogenesis by means of FSH and LH synthesis, and the impact of endocrine disruptors on this central axis regulating fertility.