What is the primary function of the testis?

The primary function of the testis is the production of sperm and testosterone. The testis is a crucial component of the male reproductive system, specifically responsible for spermatogenesis, which is the process of producing mature sperm cells necessary for reproduction. In addition to sperm production, the testis secretes testosterone, a key male sex hormone that plays an essential role in the development of male reproductive tissues, the promotion of secondary sexual characteristics, and the regulation of other physiological processes.

This differentiation in function is significant in comparing it to other options. For instance, the production of insulin and regulation of blood sugar is a function of the pancreas, not the testis. The metabolism of hormones and detoxification of substances primarily occurs in the liver. Lastly, the regulation of blood calcium and phosphate levels involves the parathyroid glands and kidneys, which oversee these specific functions. Therefore, the testis's unique role in producing sperm and testosterone underscores its primary biological function in male reproductive health.