The expression of corticosteroids and regional expression 16 (CR16) and neural Wiscott-Aldrich syndrome protein (N-WASP) was studied in the testes of men with idiopathic azoospermia by (1) immunohistochemistry and Western blot to detect the expression of CR16 and N-WASP protein, (2) reverse transcription with the polymerase chain reaction (RT-PCR) to determine the amounts of CR16 and N-WASP mRNA, and (3) double-staining immunofluorescence and laser scanning confocal microscopy (LSCM) to demonstrate the co-localization of CR16 and N-WASP proteins.