It is possible for men to remain fertile throughout their lives,
well into their old age. Men's sperm is contained in the semen.
Sperm are made in the testicles. Sperm swim into the sperm tubes
(called the epididymis) in the scrotum. There are two of these
tubes, one on each side, attached to the testicle and connecting to
the urethra, the tube in the penis. The sperm are carried in fluid
called semen which is produced by various glands including the
prostate. Anything that affects the testicles can affect sperm
production and therefore the ability to have children.
Any procedure which removes one testicle will lessen the amount of
sperm produced, but fertility would remain. Removal of both
testicles would obviously make a man infertile as there is no place
left to make sperm. When infertility is a possible result of any
condition being treated either by surgery, drug treatment or
radiotherapy (radiation treatment) it may be worth considering have
sperm saved beforehand in a sperm bank for later use.