Final answer:
The testes are male reproductive glands that produce sperm and secrete the hormone testosterone, which is responsible for the development of male sexual characteristics.
Step-by-step explanation:
Testes and Testosterone
The testes (singular = testis) are male reproductive glands responsible for producing sperm cells and secreting hormones. As male gonads, they perform two critical functions in the male reproductive system. Firstly, they produce sperm, which are the male gametes crucial for reproduction. Secondly, the testes secrete testosterone, which is the primary male sex hormone responsible for the development and maintenance of male secondary sexual characteristics.
Contained within the scrotum, the testes are replete with seminiferous tubules where the stages of sperm production occur. Cells known as Sertoli cells are found within these tubules and aid in the nurturing and development of sperm. Interspersed between these tubules are Leydig cells, which are specifically responsible for secreting testosterone. This hormone plays a pivotal role in regulating sex drive, muscle strength, bone mass, and the production of red blood cells and sperm in males.
Aside from these functions, testosterone also triggers and maintains the male's reproductive system development, contributing to the growth spurt during puberty and the emergence of characteristics such as facial and body hair, and a deeper voice. The testes continue to produce sperm and secrete testosterone throughout the male's reproductive lifespan.