MAMMALIAN TESTIS 



319 



.1 





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Fig. 5.6. Vascular patterns of the testi.- ni ,i i. \\ maniinals. Roentgenograms of testicular 

 artery injected with opaque medium from (1 ) (.log, (..^) goat, (3) ram, (4) mouse, (5) rat, (6) 

 rabbit, (?) guinea pig, (S) cat, and (9) monkey. (From R. G. Harrison and J. S. Weiner, 

 J. Exper. Biol., 26, 304, 1949.) 



perature gradient depends on many factors, 

 such as the convolutions of the artery, the 

 length of the artery, the size of the testis, 

 the relationship between veins and arteries, 

 and the activity of the dartos muscle (Har- 

 rison and Weiner, 19491. 



Inasmuch as temperature affects the testis 

 directly, and also indirectly by way of the 

 circulatory system, it is necessary to deal 

 separately with the direct effects of tem- 

 perature on the testis, the effects of envi- 

 ronmental temperature, and the effects of 

 circulatory occlusion. It is generally agreed 

 that heat applied locally is injurious to the 

 testis. Moore's experiments in which the 

 testes were wrapped in insulating material 



already have been mentioned. In the guinea 

 pig, sex activity and fertility are depressed 

 for 44 to 72 days after exposure to heat 

 (Young, 1927). Similar effects may be ob- 

 tained (Williams and Cunningham, 1940) 

 by heating rat testes with infrared lamps 

 or by heating dog testes with microwaves 

 from a radar source (Williams and Carpen- 

 ter, 1957). In men, a single bout of fever 

 (MacLeod and Hotchkiss, 1941) that in- 

 creased the body temperature to 40.5°C. 

 caused a depression in the sperm count. 

 After return of the sperm count to normal, 

 another episode of fever induced another 

 depression. The production of androgen is 

 not affected by exposure to high environ- 



