Influence of abdominal temperature and luminal contents on the cauda epididymidis of the rat

In an attempt to determine if changes previously described in the epididymides of cryptorchid testes were related to the elevated environmental temperature or to the absence of normal luminal constituents, rats were divided into four test groups. Group I animals were made unilaterally cryptorchid. Animals in Group II had only the cauda epididymidis of one side maintained within the abdominal cavity (cryptepididymal) while the caput epididymides and testes remained in the scrotum. The testes of animals in Group III remained in the scrotum but had their efferent tubules ligated on one side. Testes of unoperated rats and contralateral testes of the test animals served as controls. The histochemical demonstration of sorbitol dehydrogenase (SDH) was used to determine differences in functional activity and light and electron microscopy were used to determine structural changes. SDH activity could not be demonstrated in the cauda epididymidis of cryptorchid and efferent tubule-ligated animals; animals in which the luminal contents were obviously changed. These same groups of animals showed abnormal folding of the basal surface of the epididymal epithelium at the ultrastructural level. Activity of SDH could be demonstrated in control epididymides and in those that contained normal luminal contents but were maintained at the temperature of the abdominal cavity. The basal surface of the epididymal epithelium was not unusual in these animals. The results indicate that the epididymis is influenced to a greater extent by changes in luminal contents than by temperature elevation.