Pubic hair staging is related both to quantity and distribution (Fig. 29.4). In Tanner stage 1, there is no sexually stimulated pubic hair present, but some nonsexual hair may be present in the genital area. Tanner stage 2 is characterized by the first appearance of coarse, long, crinkly pubic hair along the labia majora. In Tanner stage 3, coarse, curly hair extends onto the mons pubis. Tanner stage 4 is characterized by adult hair in thickness and texture, but the hair is not distributed as widely as in adults and typically does not extend onto the inner aspects of the thighs. Except in certain ethnic groups, including Asians and American Indians, pubic hair extends onto the thighs in Tanner stage 5.
Figure 29.2 Schematic sequence of events at puberty. An idealized average girl and an idealized average boy are represented. (From Rebar RW. Practical evaluation of hormonal status. In: Yen SSC, Jaffe RB, eds. Reproductive endocrinology: physiology, pathophysiology and clinical management. 3rd ed. Philadelphia, PA: WB Saunders, 1991:830, with permission; based on data from Marshall WA, Tanner JM. Variations in patterns of pubertal changes in girls. Arch Dis Child 1969;44:291–303, and Marshall WA, Tanner JM. Variation in the pattern of pubertal changes in boys. Arch Dis Child 1970;45:13–23, with permission.)
The staging of male pubertal sexual maturation is based on genital size and pubic hair development. Tanner stage 1 is prepubertal. Tanner stage 2 of genital growth begins when testicular enlargement is first evident. Testis length along the longitudinal axis ranges from 2.5 to 3.2 cm. The size of the penis increases. Pigmented, curly pubic hair is first visible around the base of the penis. In Tanner stage 3, there is further growth of the penis in both length and diameter, the scrotum develops further, and testis length increases to 3.3 to 4 cm. Thicker, curly hair extends above the penis. Tanner stage 4 involves further growth of the genitalia, with testis length ranging from 4 to 4.5 cm. Extension of pubic hair over the genital area continues, but the volume is less than in the adult. At this stage, the prostate gland is palpable by rectal examination. In Tanner stage 5, the genitalia are within the adult range in size. Average ﬂaccid penile length in adult men ranges between 8.6 and 10.5 cm from tip to base. Pubic hair spreads laterally onto the medial thighs. Hair may or may not extend from the pubic area toward the umbilicus and anus.
Pigmented pubic hair is often the first recognized sign of male puberty even though it typically occurs 6 months after genital growth begins. Tanner stage 3 puberty often is accompanied by symmetric or asymmetric gynecomastia, and mature sperm first can be identified with microscopic urinalysis.
Figure 29.3 Diagrammatic depiction of Tanner breast stages in adolescent women. (From Ross GT, Van de Wiele RL, Frantz AG. The ovaries and the breasts. In: Williams RH, ed. Textbook of endocrinology. 6th edition. Philadelphia, PA: WB Saunders, 1981:355, with permission; adapted from Marshall WA, Tanner JM. Variations in patterns of pubertal changes in girls. Arch Dis Child 1969;44:291–303).