Insulin-like 3 plays a role in testicular function. Insulin-like 3 is a trophic hormone with a role in testicular descent in fetal life. Insulin-like 3 is a ligand for LGR8 receptor. Insulin-like 3 is a heterodimer of a B chain and an A chain linked by two disulfide bonds. Defects in insulin-like 3 are a cause of cryptorchidism (CRYPTO), also known as impaired testicular descent. CRYPTO is one of the most frequent congenital abnormalities in humans, involving 2-5% of male births. CRYPTO is associated with increased risk of infertility and testicular cancer.