Steroids in fluids and sperm entering and leaving the bovine epididymis, epididymal tissue, and accessory sex gland secretions.

Ten steroids which may have a role in the process of sperm maturation within the epididymis were quantified by competitive protein binding or radioimmunoassay. Rete testis fluid (RTF) carrying testicular sperm into the epididymis was rich in dehydroepiandrosterone and testosterone (21 +/- 2 and 33 +/- 3 ng/ml) while cauda eipididymal plasma (CEP) around sperm which have completed maturation had high levels of progesterone, dihydrotestosterone, 3beta-androstanediol, dehydroepiandrosterone and testosterone (7.4 +/- 0.8, 20.3 +/- 1.1, 6.5 +/- 0.4, 8.0 +/- 0.7 and 11.5 +/- 0.7 ng/ml). About 4 mug of steroids enter the epidymis daily in RTF, but less than 1% was found in CEP; the balance presumably was absorbed by the epithelium in the proximal caput epididymidis. Nevertheless, tissue levels of total 17beta-OH androgens were lower in the proximal caput than in the distal caput or corpus epididymidis. In all zones of the epididymis, dihydrotestosterone accounted fro about 70% of the total 17beta-OH androgens found in the nuclear fraction. In the cytoplasmic fraction, however, dihydrotestosterone predominated only in the distal caput and corpus epididymidis. In the cauda epididymidis, CEP and sperm probably accounted for less than 35% of the total 17beta-OH androgens and less than 25% of the dihydrotesterone. The progesterone concentration of the cauda than in the caput epidymidis. Twice washed testicular sperm contained more testosterone than cauda epididymal or ejaculated sperm (16.6 +/- 1.9, 1.6 +/- 0.2 and 1.5 +/- 0.3 ng/10(9) sperm, respectively), but less progesterone (0.5 +/- 0.1, 1.3 +/- 0.2 and 1.0 +/- 0.4 ng/10(9) sperm, respectively). As a consequence of mixture with estrogen-rich prostatic fluid (150 +/- 9 pg/ml), ejaculated sperm contained a relatively high amount of estrogens (112 +/- 15 pg/10(9) sperm). These studies revealed marked differences in steroid profiles of fluids entering and leaving the epididymis and of infertile testicular and fertile cauda epididymal sperm.