Papilla (nipple) development in puberty. The adolescent male

Papilla (nipple) development was studied in 230 males (119 black, 111 white) aged 3-29 years to compare this development to the established criteria for sexual maturation. Comparison was also made with a previous study of female nipple development to determine whether or when any differences between male and female nipple development occurred. Our male subjects were further assessed to determine if nipple size differed in the presence or absence of gynecomastia. Significant nipple development occurred between pubic hair stages PH1 (diameter 2.8 mm), PH4 (4.4 mm), and PH5 (5.4 mm). Similarly, there was significant incremental growth between genital stages G1 (3.0 mm), G3 (4.6 mm), and G5 (5.5 mm). Nipple development was similar in both sexes through stage PH3, but significantly diverged at stage PH4 (p less than 0.000001) because of a marked increase in female nipple diameter. Boys with gynecomastia had a significantly larger nipple size than boys who had none (p less than 0.001). Differences in nipple diameter between the sexes and between boys with and without gynecomastia probably result from differences in estrogen levels. Perhaps in the future, it will be possible on the basis of nipple diameter to predict which adolescent boys will have persistent gynecomastia.