nMale gametes often
exhibit abnormal or completely curtailed development when exposed to elevated temperatures.
nConsequently, both
the male gonads and the first portion of the duct system, which is the site of early sperm maturation
and development, reside outside the body proper within a skin-covered sac called the scrotum.
nWhen the testes are
exposed to elevated temperatures, the skin of the scrotal sac becomes thin as a result of dartos relaxation.
nAt the same time,
another muscle (the cremaster muscle) relaxes to allow the testes to move inferiorly away
from the body. The testes
temperature becomes less than normal body temperature.
nThe opposite occurs if the testes are exposed to cold.