The epididymis receives sperm
from the seminiferous tubules
of the testis
and stores it.
It takes about 20 days for sperm to pass through the 6-m-long tubules of each epididymis of a human male. During this passage, the sperm become motile and gain the ability to fertilize.
During ejaculation, the sperm are propelled from the epididymis through the muscular vas deferens.