WISH of f8 expression in wild-type zebrafish larvae at 5 dpf. (A) In situ hybridization with an antisense probe shows f8 expression in the heart, while a sense control probe shows no signal. Scale bars, 500 μm. f8 expression is located in the atrial and ventricular walls of the heart as shown in (B) sagittal and (C) transverse sections (10 μm) of stained larvae.