Fish embryo culture: cardiac monolayers and contractile activity in embryo explants from the zebrafish, Brachydanio rerio

Stage 16+ axial isolates from embryos of the zebrafish, Brachydanio rerio (Hamilton-Buchanan), were separated from their yolk spheres and epidermis. Rhombencephalic level explants, with intact bilateral cardiac rudiments, were maintained in nutrient medium for 20 days at 24 ± 2 °C. All embryo cultures became attached to the culture substrate and underwent subsequent differentiation. Ten out of 25 explants showed bilateral migrations of determined but initially undifferentiated cardiac mesoderm. The progressive structural and functional differentiation of zebrafish cardiac monolayers and intact rudiments are described for the first time.