Final answer:
The onset of production of semen is called spermatogenesis, which begins at puberty and results in mature sperm stored in the epididymis until ejaculation.
Step-by-step explanation:
The onset of production of semen is called spermatogenesis. This biological process begins at puberty and involves the production of sperm cells through a series of steps taking place in the seminiferous tubules of the testes. The mature sperm then move to the epididymis, where they continue to develop. Once fully mature, these sperm are stored until ejaculation, during which they are expelled from the body in the seminal fluid, collectively known as semen.
During the production of semen, not only sperm are produced; the bulk of semen consists of fluids secreted by the male reproductive accessory glands. These fluids and sperm mixed together create the semen that is ejaculated during the male orgasm, during which sperm are propelled from the epididymis out through the urethra in semen.
While spermatogenesis occurs continuously from puberty throughout a man's life, dietary and lifestyle factors such as nutrition and smoking can affect semen production. It's important to note that total sperm counts and sperm quality may decline with advancing age.