Condensing mesenchyme of the early pectoral fin bud. Morphogenesis of the pectoral bud during the late pharyngula period. Refractile tail reticular cells line sinusoids that make up the wall of the developing caudal vein. Development during the hatching period of embryogenesis and the early larva. Jaw cartilage and muscle formation is well underway by the end of the hatching period.
Branchial arches develop late in embryogenesis.
The appearance of the cleithrum, the first easily visible bone, marks the end of embryogenesis.