Inhibin + Androgen binding protein + Estrogen

Inhibin

Is a protein that selectively inhibits the synthesis and secretion of FSH by the pituitary gonadotropes.

Androgen binding protein

Is protein that binds androgens. It is found both in the luminal fluid and plasma. ABP is concentrated in the luminal fluid and in the epididymis and its role is to carry testosterone within the sertoli cells and from the testis to the epididymis in order to maintain high testosterone concentration.

Estrogen

The principle estrogens in the plasma of adult males are estradiol and estrone, only 10%-20% of the circulatory estrogens are synthesized by sertoli cells in the testis, the remainder originate through the extra gonadal conversion of testosterone and androstenedione.