Expression of bone morphogenetic protein 7 in murine epididymis is developmentally regulated

Bone morphogenetic proteins (BMPs) have been shown to play a role in the functional maintenance of the adult epididymis. To begin to investigate the role of BMP signal transduction during postnatal epididymal development, we examined the expression profile of Bmp7 in murine epididymis by in situ hybridization. Our data show that during early postnatal development (younger than 3 wk of age), Bmp7 transcripts are detected uniformly in epithelial cells throughout the epididymis. As the mice aged (from 3 to 4 wk), Bmp7 expression was gradually restricted to the initial segment, with increased levels. Bmp7 expression in the rest of the caput and corpus regions became undetectable after 4 wk of age. However, after 4 wk of age, an ascending gradient of Bmp7 expression was observed in the epididymal epithelial cells in the transition from the cauda epididymal tubule to the vas deferens. Such a unique expression profile of Bmp7 strongly suggests that epididymis-produced BMP7 may play a role in the development and functional maintenance of the epididymis, and that Bmp7 expression in the epididymis is developmentally regulated.