Expression of bmp2a and bmp2b in late-stage zebrafish median fin development.

Zebrafish bmp2a and bmp2b mRNA expression in the developing median fins (caudal, anal, and dorsal) of late-stage larvae (>5 days post-fertilization) was analyzed by reverse transcriptase-PCR (RT-PCR) and in situ hybridization. bmp2a is expressed in developing fin rays, while bmp2b is expressed in developing fin rays, hypertrophic chondrocytes, and in the zone of segmentation (ZS) in developing anal and dorsal fin radials. This latter pattern of bmp2b expression in the ZS mirrors tetrapod bmp2 expression in developing joints.