Figure 3.

Morphological features and expression patterns of Isl1 in the St29/30 ((a), (b)) and St31 ((c), that Isl1 is also expressed by undi (d)) Xenopus laevis retina. ((a), (c)) Toluidine blue-stained transverse retinal resin sections showed that the neural retina had the structure of pseudostratified columnar epithelium. Notice that during these early stages abundant dark-stained granules were observed in the cytoplasm of the neuroepithelial cells. (b),(d) Isl1 immunoreactivity was present in sparse nuclei mainly located near the vitreal surface (arrowheads). L: lens; NbL: neuroblastic layer. Scale bar: 50 μm.