Tissue immunoexpression and messenger ribonucleic acid localization of inhibin/activin subunit in human epididymis.

OBJECTIVE

To determine the expression of inhibin betaA and betaB subunits and follistatin and the ability of human epididymal epithelium to synthesize these molecules.

DESIGN

The main aim of this study was to investigate the expression of inhibin alpha, betaA, and betaB-subunits and follistatin in human epididymis with immunohistochemistry, in situ hybridization, and Western blotting in adult life.

SETTING

Academic university hospital.

PATIENT(S): Epididymes were obtained from 10 men undergoing routine vasectomy or surgery for benign disease at the Royal Hallamshire Hospital, Sheffield, United Kingdom.

MAIN OUTCOME MEASURE(S): Immunoexpression of activin betaA and betaB subunits and follistatin proteins and mRNA in human caput and cauda epididymis.

RESULT(S): Positive immunoexpression for activin betaA and betaB subunits and follistatin were detected in different parts of the epididymis epithelium. Western blotting under a reducing condition detected a 28-kd band (possibly corresponding to the activin dimer). In situ hybridization indicated positive mRNA localization signal in both caput and cauda epididymal epithelium.

CONCLUSION(S): Activins betaA and betaB subunits, but not inhibin alpha subunit, were detected in epididymal epithelium. These finding suggest that activins might have a role in the processes of sperm maturation and sperm fertilizing capability during transit and storage.