Final answer:
Emission is the last event in the male sex act that results in ejaculation, following processes such as sperm maturation, vasodilation, and testosterone production.
Step-by-step explanation:
The event in the male sex act that occurs last and results in ejaculation is emission. During the sexual response, prior to ejaculation, a series of events take place which include sperm maturation, which occurs in the epididymis where sperm also get stored; vasodilation, which is necessary for an erection; and testosterone production, which promotes sexual development and normal spermatogenesis. The process of spermatogenesis happens in the seminiferous tubules located in the testes. However, when it comes to actual ejaculation, it is the process of emission that leads to the forceful expulsion of semen from the urethra.