
324 Second Harmonic Generation Imaging
the end of the segmentation period, 24 hpf, 30 pairs of somites will be completely formed. By observing
an 11-hpf (three-somite stage) zebrash embryo from its dorsal side (Figure 14.11a), the anterior-most
completely formed three somites (somite 1–3) and also the pinching o of the fourth somite (arrow) are
clearly revealed by THG modality. At this stage, the fourth somite is just beginning to form and appears
as a circumscribed region called “somitomere.” Figure 14.11b shows the le-side view of the structures
of the readily formed ve somites at the ve-somite stage. Since no muscle bers have developed ...