The local expression of adult chicken heart myosins during development. I. The three days embryonic chicken heart.

Immunofluorescence studies were performed on serial sections of three days embryonic chicken hearts using antibodies specific for adult atrial and ventricular myosin heavy chains respectively. The anti-ventricular myosin serum reacted with the entire myocardium showing a decreasing intensity going from the truncus arteriosus to the atrial part; however, the antiatrial myosin serum reacted weakly with the myocardium of the atrial part. Two other interesting observations were made, i) the anti-atrial myosin serum reacted with non-myocardial cells in the cardiac jelly, ii) both antisera reacted with a thin myocardial layer, extending from the ventral wall of the atrial part via the medio-dorsal wall of the atrio-ventricular canal to the dorsal wall of the ventricular part.