In girls, the 1st visible sign of puberty and the hallmark of SMR 2 is the appearance of breast buds, between 8 and 12 yr of age. Menses typically begins 2-2.5 yr later, during SMR3-4 (median age, 12 yr; normal range, 9-16 yr). Less obvious changes include enlargement of the ovaries, uterus, labia, and clitoris, and thickening of the endometrium and vaginal mucosa.
In boys, the 1st visible sign of puberty and the hallmark of SMR2 is testicular enlargement, beginning as early as 9.5 yr. This is followed by penile growth during SMR3. Peak growth occurs when testis volumes reach approximately 9-10 cm3 during SMR4. Under the influence of LH and testosterone, the seminiferous tubules, epididymis, seminal vesicles, and prostate enlarge. The left testis normally is lower than the right. Some degree of breast hypertrophy, typically bilateral, occurs in 40-65% of boys during SMR2-3 due to a relative excess of estrogenic stimulation.
|SMR STAGE||PUBIC HAIR||BREASTS|
|2||Sparse, lightly pigmented, straight, medial border of labia||Breast and papilla elevated as small mound; diameter of areola increased|
|3||Darker, beginning to curl, increased amount||Breast and areola enlarged, no contour separation|
|4||Coarse, curly, abundant, but less than in adult||Areola and papilla form secondary mound|
|5||Adult feminine triangle, spread to medial surface of thighs||Mature, nipple projects, areola part of general breast contour|
|SMR STAGE||PUBIC HAIR||PENIS||TESTES|
|2||Scanty, long, slightly pigmented||Minimal change/enlargement||Enlarged scrotum, pink, texture altered|
|3||Darker, starting to curl, small amount||Lengthens||Larger|
|4||Resembles adult type, but less quantity; coarse, curly||Larger; glans and breadth increase in size||Larger, scrotum dark|
|5||Adult distribution, spread to medial surface of thighs||Adult size||Adult size|