Biomedical Engineering Reference
In-Depth Information
FIgurE 14.10
SHG/THG images of the zebrafish eye. (a) The left eye of a live 14-somite-stage embryo with the
left side to the top. The flat tissue named optic vesicle (OV) and the silt, optic lumen (OL, arrow), are shown by
THG; at this stage (b) only few SHG from mitotic spindles can be found near the optic lumen. (c) The left eye of
a live prim-15-stage embryo. The lens (L) and retina (R) are clearly observed through THG and the nerve fibers
elongated across the retina are picked up by SHG, respectively. (d) The eye of a live 60-hpf embryo. By superimpos-
ing each section at different depths, the optic nerve from the lens (L) to the neural tube is revealed by SHG (arrow).
(e) SHG/THG image obtained from a paraffin section of a 4-day eye. Strong SHG can be found in layers full of
nerve fibers (arrowheads), optic nerve (dotted arrow), and the outer segment of the photoreceptor (arrow). Scale
bar: 100 μm for (a), (c), (d), and (e); 10 μm for (b). SHG images corresponding to (b)-(e) are shown in (b-S)-(e-S),
respectively.
the end of the segmentation period, 24 hpf, 30 pairs of somites will be completely formed. By observing
an 11-hpf (three-somite stage) zebrafish embryo from its dorsal side (Figure 14.11a), the anterior-most
completely formed three somites (somite 1-3) and also the pinching of 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 left-side view of the structures
of the readily formed five somites at the five-somite stage. Since no muscle fibers have developed yet at
the three-somite and five-somite stages, no SHG signals can be observed. In an 18-somite-stage (18 hpf)
embryo with left side to the top (Figure 14.11c), THG signals show the small vacuoles (arrow) within
the notochord cells and the structures of the somites, while in a 20-somite-stage (19 hpf) embryo with
dorsal side to the top (Figure 14.11d), SHG signals appear to show muscle fibers in the somites. At the
prim-15 stage (30 hpf), the SHG-revealed muscle fibers are found to become much straighter and denser,
while the THG-revealed vacuoles are observed to become larger (Figure 14.11e). At 48 hpf, the straight
