Final answer:
Sertoli cells provide nourishment and support to developing sperm cells. They secrete signaling molecules promoting sperm production and create a barrier to prevent harmful substances from reaching the germ cells.
Step-by-step explanation:
Sertoli cells provide nourishment and support to developing sperm cells. They are a type of supporting cell that secrete signaling molecules promoting sperm production and control whether germ cells live or die. Sertoli cells create the blood-testis barrier, which prevents bloodborne substances from reaching the germ cells and maintains surface antigens on developing germ cells within the testes.