Early morphogenesis of the neural primordium. Sculpturing of the brain rudiment during the segmentation period. Cells of the trigeminal placode will form sensory neurons of the trigeminal ganglion. Morphogenesis of the otic vesicle. Development during the pharyngula period.
Neural structures predominate in the head during the pharyngula period.
Fig. 31 . Cells of the hatching gland, present on the pericardium over the anterior yolk sac have prominent granules during the pharyngula period. The posterior lateral line primordium, and underlying structures along the flank of the pharyngula. Condensing mesenchyme of the early pectoral fin bud. Morphogenesis of the pectoral bud during the late pharyngula period.