Composition of fluids obtained from human epididymal cysts.

The fluid composition of five epididymal spermatocoeles, one epididymal cyst and a hydrocoele was examined. The fluid obtained from the spermatocoeles was a dilute suspension of mainly immotile spermatozoa. The sperm-free fluid contained less protein, phosphate, glucose, triglyceride and cholesterol than serum but more testosterone and chloride than peripheral blood. It contained no epididymal secretion products. Proteins in the fluid differed from those in serum. From the fluid composition these cysts appeared to be continuous with the rete testis, either dilatations of efferent ducts or Haller's superior aberrant duct (vas aberrans of the rete testis). Fluid from an epididymal cyst containing no spermatozoa was mainly of similar composition. In contrast, hydrocoele fluid resembles blood serum.