Final answer:
Sertoli cells, located in the seminiferous tubules, are crucial for spermatogenesis, providing nourishment and protective barriers for developing sperm.
Step-by-step explanation:
Sustentacular cells, also known as Sertoli cells, are located within the seminiferous tubules of the testes. They play a vital role in spermatogenesis by surrounding all stages of the developing sperm cells. These elongate, branching cells extend from the peripheral basement membrane to the lumen, secreting signaling molecules that promote sperm production and regulate germ cell viability. Their tight junctions form the blood-testis barrier, protecting germ cells from bloodborne substances and preventing an autoimmune response by isolating surface antigens from the blood.