Both are produced by the ovaries or testes, and by the adrenal cortex. A base level of testosterone in men is needed for spermatogenesis and for prostate and seminal vesicle action. However recent work suggests that a high level of oestrogen is also required within the testes to regulate the concentration of sperm in the semen. In men the main circulating androgen is testosterone. Oestrogen is present in small amounts, and can be synthesised from testosterone at the point where it is needed.
Progesterone is present only as a trace.
In women, androgens are present, principally as androstenedione, which can be converted to testosterone and dihydrotestosterone as needed. To summarise, then, negative feedback senses the total complement of the gonadotrophins of whatever kind, causing the hypothalamus and pituitary to reduce the output of FSH and LH and, in women, periodically, a positive feedback system is superimposed. Role in general metabolism. Looking once more at the feedback diagram at the beginning of this piece, it would seem that sperm production in men is controlled by LH concentration rather than testosterone. If fertility is the criterion of maleness, one might expect that testosterone is not absolutely essential.