Factors affecting the weight of the cremaster muscle

Abstract

The importance to the cremaster muscles of passive tension, innervation, and testosterone was determined in the rat After unilateral castration atrophy due to lack of tonus in the cremaster fibers occurred, 27 and 38% by 7 and 14 days, respectively. Denervation resulted in smaller atrophies, 18 and 24% by 7 and 14 days, respectively. When the two operations were combined the atrophy was essentially equal to the sum of the separate responses. Atrophies due to lack of tension after testis removal and after denervation were of essentially the same magnitude whether testosterone was present or not. Although injection of testosterone for 14 days induced a hypertrophy of 42% in the levator ani, an insignificant 7% increase in the weight of the cremaster occurred. In the rat the testes appear to be more important to the cremasters for tension maintenance than for secretion of testosterone.