Morphological and Endocrinological Differences between the Abdominal Testes in Bilateral and Unilateral Cryptorchid Rats

Using a new experimental model of cryptorchism in rats, where testicular descent was prevented, testicular development and function were studied in bilateral and unilateral cryptorchid animals Morphometric and radioimmunological techniques were used. Up to 30 days after birth testicular development was identical in the two types of abdominal testes but in adult rats differences were observed. In these rats spermatogenesis was damaged to a similar extent, but total tubular length and testicular weight were increased in the bilateral abdominal testes. Moreover, in these testes, the volume density of Leydig cells, the total Leydig cell mass, the average Leydig cell size and the testis testosterone concentration were larger than in unilateral abdominal testes. It is suggested that the impaired spermatogenesis seen in both kinds of abdominal testes may be unrelated to Leydig cell function.