Final answer:
The Tanner stages for males map out the sequence of pubertal development, starting with prepubertal signs at Stage I and culminating in adult maturation at Stage V.
Step-by-step explanation:
The Tanner stages describe the physical progression of puberty in males, with changes in external genitalia, growth of pubic hair, and other secondary sex characteristics. During puberty, beginning around ages 11 to 12, a series of developmental stages take place. In males, the first sign of puberty is the enlargement of testes, followed by an increase in size and pigmentation of the scrotum, and then growth of the gland. This period also includes the growth of hair (armpit, pubic, chest, facial), deepening of the voice as the vocal cords lengthen and thicken, shoulder broadening, and the adolescent growth spurt, largely driven by testosterone, which may continue into a boy's early 20s. The sequence of Tanner stages is as follows:
- Stage I: Prepubertal (average age 11)
- Stage II: Enlargement of testes and scrotal skin starts to thin and redden
- Stage III: Enlargement of the gland (length at first), further growth of testes, darkening of the scrotal skin
- Stage IV: Increased size of gland with growth in breadth and development of glans, testes, and scrotum larger; pubic hair becomes coarse, thick, and curly
- Stage V: Adult genitalia, pubic hair extends to thighs and up toward umbilicus
The changes associated with puberty such as spermarche, the first male ejaculation, appear generally around age 15 but can vary. Understanding the Tanner stages helps in gauging normal development during puberty.