Fig. 9. FRL-1 expression in neuroectoderm at the late gastrula stage. (A,B) Whole-mount in situ hybridization revealed the spatial expression patterns of FRL-1. (A) Lateral view of a stage 10 embryo; right side is dorsal. FRL-1 was ubiquitously expressed in the early gastrula. (B) Lateral view of a stage 12 embryo; right side is dorsal. Transcripts of FRL-1 are concentrated in the neuroectoderm. (C) RT-PCR analysis of chordin-injected ectoderm. Misexpression of chordin induced the expression of FRL-1 in the absence of the mesodermal marker, Xbra.