Testosterone concentrations are quite low in prepubertal boys but consistently increase after the onset of enhanced gonadotrophin secretion in early puberty, with exponential rises occurring during stages 2 and 3 of pubertal development.
The major female oestrogen, oestradiol, is secreted mainly by the ovary, although a small amount arises from extraglandular conversion of testosterone and androstenedione. Oestradiol increases during pubertal development and then varies in association with the stage of the menstrual cycle.
