temperature is increased (regardless of the cause), sperm morphology is generally unaffected initially (for an interval corresponding to epididymal transit time) but subsequently declines. In some studies [29, 33], sperm in the epididymis at the time of scrotal heating were morphologically abnormal when collected soon after heating. In another study [30], changes in these sperm were manifest only after they were frozen, thawed, and incubated. Sperm morphology usually returns to pretreatment values within approximately six weeks after the thermal insult. However, a prolonged and/or severe increase in testicular temperature will increase the interval for recovery. In general, the decrease in semen quality following increased testicular temperature is related to severity and duration of the thermal insult.
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