[Central European study of the development of secondary sex characteristics in girls. I. Axillary hair as the 4th secondary sex characteristic].

As a part of the Central European Study a long-term study of the pubertal development of 687 Hungarian girls was undertaken and the findings compared with those of a cross-sectional study of a group of girls from Münster. In addition to assessment of the breast and pubic hair according to Tanner's classification, the development of axillary hair was, for the first time, subdivided into five stages (A1 to A5). This pubertal feature was related to the characteristics already known and, because of the absence of literature, compared with the author's own data. Stage A1 is the infantile stage, in which there is no hair development. In Stage A2, isolated, long, barely visible hairs appear. Stage A3 is marked by the development of a narrow band of sparse hair. In Stage A4 the area covered by hair is larger, and the hair has become more dense. Stage A5 is the adult stage, with a longish, rectangular area covered by hair of a density and texture found in adults. The development of axillary hair began at a average age of 11.94 years, with a standard deviation of 0.93 years. The subsequent stage (A3) was reached at a mean age of 12.53 +/- 0.92 years. At age 12.99 +/- 0.87 years Stage A4 was well developed. The adult hair covering appeared at a mean age of 13.58 +/- 0.66 years. The mean duration of development of the axillary hair was 2.28 +/- 0.60 years. Axillary hair was generally the last pubertal characteristic of development. Only in 5.5% of the girls was axillary hair the first sign of puberty.