Puberty: Gonadarche and Adrenarche

Puberty in humans is defined as the period of becoming capable of reproducing. It is marked by maturation of the genital organs, development of secondary sex characteristics, acceleration in linear growth velocity, and, in the female, the occurrence of menarche. Many factors influence the age at onset and the tempo at which puberty progresses. The age at puberty may be associated with health consequences later in adulthood. Normal function of the hypothalamic-pituitary-gonadal (HPG) axis is dependent on the meticulous spatio-temporal orchestration of gonadotropin-releasing hormone (GnRH) neuron development in the hypothalamus. While the neurobiological mechanisms that underlie GnRH pulse generation remain controversial, compelling evidence indicates the fundamental role of KNDy neurons in the arcuate nucleus. Identification and investigation of specific mutations in families with disorders of puberty have established some of the factors involved in GnRH neuron migration and gonadal function. This chapter reviews the disorders of puberty in the context of the development and maturation of the HPG axis. Elucidation of the neurobiology of the GnRH neurons and the developmental processes unfolding during gonadal and adrenal maturation will improve understanding of the pathophysiology of the disorders of puberty and, perhaps, lead to novel therapies. © 2019 Elsevier Inc. All rights reserved.