HCG treatment increases intratesticular pressure in the abdominal testis of unilaterally cryptorchid rats.

Adult, unilaterally cryptorchid rats were given a single subcutaneous injection of hCG. HCG treatment of 100 I.U. (but not 10 I.U.) resulted in a marked increase in intratesticular pressure (approximately 40 mm Hg) in the abdominal testis that was maximal 24 hours after treatment. This increase in pressure is caused by increased vascular permeability coupled with insufficient lymph drainage. In the scrotal testis, hCG treatment resulted in increased vascular permeability and lymph flow, but this did not result in a marked increase in testicular pressure. No morphologic signs of hCG-induced damage were observed in either the abdominal or scrotal testis 10 days after hCG treatment. Testicular microcirculation, as studied by laser doppler flowmetry, was abnormal in the abdominal testis, but hCG treatment inhibited vasomotion in both the abdominal and scrotal testis.