Age-dependent expression of the cystatin-related epididymal spermatogenic (Cres) gene in mouse testis and epididymis.

AIM To investigate the spatial and temporal expression of the cystatin-related epididymal spermatogenic (Cres) gene in mouse testis and epididymis during postnatal development. METHODS The QuantiGene assay and indirect immunofluorescence technique were used to examine the Cres mRNA and Cres protein level in mouse testis and epididymis on postnatal days 14, 20, 22, 28, 35, 49, 70 and 420. RESULTS (1) In both the testis and epididymis, Cres mRNA was first detected on day 20, then it increased gradually from day 20 to day 70, and the high expression level maintained till day 420. (2) In the testis, the Cres protein was exclusively localized to the elongating spermatids and was first detected on day 22. The number of Cres-positive spermatids increased progressively till day 49. From day 49 to day 420, the number of Cres-positive cells was almost stable. (3) The Cres protein was first detected on day 20 in the proximal caput epididymal epithelium. By day 35, the expression level of the Cres protein increased dramatically and the high level was maintained till day 420. Moreover, the luminal fluid of the midcaput epididymis was also stained Cres-positive from day 35 on. No Cres-positive staining was observed in distal caput, corpus and cauda epididymis throughout. CONCLUSION The Cres gene displays a specific age-dependent expression pattern in mouse testis and epididymis on both the mRNA and protein level.