Final answer:
Sertoli cells do not secrete androgens like testosterone; that function is performed by Leydig cells. Instead, Sertoli cells provide support and nutrients to developing sperm, form the blood testis barrier, and secrete paracrines that stimulate spermatogenesis.
Step-by-step explanation:
The function that is NOT a characteristic of Sertoli cells is secreting androgens. Sertoli cells, also known as sustentacular cells or sustintocytes, do not secrete testosterone; this function is carried out by the interstitial cells of Leydig. Sertoli cells do indeed secrete fluid into the lumen of seminiferous tubules to support sperm development, provide nutrients for developing sperm, form the blood-testis barrier, and secrete paracrines that stimulate spermatogenesis. Therefore, they play a pivotal role in the support and nourishment of developing sperm and protection against autoimmune response, but androgen secretion is not one of their functions.