Effects of prolonged high temperature on testicular development and fertility in the male rat

High temperatures for more than 2 days in a large rat production colony resulted in the death of one-third of the animals. The temperature in the room was as high as 89 degrees F (31.6 degrees C) and it is estimated that temperatures in individual cages reached 100 degrees F (37.7 degrees C). In addition to the deaths, 25% of the surviving males, 4-66 days of age at the time of exposure to the high temperature, were found after 18 days, to have irreversible bilateral testicular atrophy. These animals were sterile whereas survivors with normal testes bred successfully.