Dynamics of androgen and oestrogen production in normal men and in patients with gynaecomastia.
Average production rates of androgen are indicated in the upper boxes, those of oestrogen in the lower boxes. The extent of conversion (per cent) of plasma testosterone and androstenedione to oestradiol and oestrone is shown by vertical arrows, and interconversions of oestradiol and oestrone, and of testosterone and androstenedione, are indicated by horizontal arrows. Sources of oestradiol and oestrone are indicated by vertical bars. Blue bars indicate oestrogen that is secreted directly by the testis. Thus, oestradiol arises from plasma testosterone, from oestrone, and from direct secretion by the testis; and oestrone arises from plasma androstenedione, from oestradiol, and, in some instances, by direct secretion from the testis, Modified from AG Frantz and JD Wilson ( 1992) by courtesy of WB Saunders.
