Tanner Stages

Excerpt

Puberty is a time of rapid and complex changes involving overlapping components: hormonal, physical, and cognitive. Tanner Staging, also known as Sexual Maturity Rating (SMR), is an objective classification system that providers use to document and track the development and sequence of secondary sex characteristics of children during puberty. It was developed by Marshall and Tanner while conducting a longitudinal study from the 1940s to the 1960s in England. Based on observational data, they developed separate scales for the development of external genitalia: phallus, scrotum, and testes volume in males, breasts in females, and pubic hair in both males and females.

The physical changes of puberty require a concerted effort from many organs; these changes are initiated by activating the hypothalamic-pituitary-gonadal (HPG) axis (gonads refer to ovaries in females and testes in males). The first hormonal change in puberty is the pulsatile release of GnRH triggered by disinhibition of the hypothalamic-pituitary-gonadal (HPG) axis. Although the cause of this disinhibition is largely unknown, the subsequent release of GnRH stimulates the pulsatile release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH and FSH act on specific gonadal cells to stimulate the release of androgens, estrogens, and gametogenesis. LH stimulates the theca cells in the ovary to produce estrogen precursors and the Leydig cells of the testes to produce testosterone. On the other hand, FSH works on the ovarian follicle to convert the thecal estrogen precursors to estrogen and on the Sertoli cells in the seminiferous tubules of the testes to help create sperm. This complex process leads to increased estrogen and testosterone production that then facilitates the development of breasts and the formation of adult male genitalia.

The adrenal glands also contribute to the formation of secondary sex characteristics, particularly pubarche, which is the development of pubic and axillary hair. Although adrenal maturation often coincides with HPG axis maturation, it is important to note that these processes occur independently and that pubarche itself is not the best indicator of pubertal development.