What are the main functions of the Sertoli cells?

(1) They stimulate the early mitosis and meiosis of the developing spermatozoa and provide them nourishment. Sertoli cells serve numerous functions.

(2) The intercellular junctions between adjacent Sertoli cells constitute the blood-testis barrier.

(3) They produce inhibin:

(4) they secrete androgen-binding globulin (ABP) which has high affinity for testosterone and is responsible for the maintenance of high intra-tubular testosterone levels by concentrating testosterone in tubular lumen.

(5) They produce mullerian duct inhibiting factor (MIF);

(6) They also secrete transferrin for transporting iron to tubular cells; ceruloplasmin for transporting copper to the tubular cells; and plasminogen activator which may mediate proteolytic reactions important for migration of maturing germ cells from the basal compartment to the adluminal compartment.

(7) Sertoli cells secrete small amounts of estrogens. They produce aromatase, the enzyme which converts androgens produced by the Leydig cells to estrogens which although contribute little to the circulating pool, may play intra-testicular roles, e.g., it binds to specific receptors in the Leydig cells and inhibit androgen production.

(8) They absorb the unnecessary cellular organelles that are cast off from the spermatozoa.

(9) They have receptors for (and hence, are stimulated by) both FSH and LH.