Neural differentiation Amphibia 2 Anura 2 Bowman membrane 2 Bufo arenarum 2 Flk-1 2 Olfactory epithelium 2 Toad 2 VEGF 2 animal cell 2 animal experiment 2 animal tissue 2 article 2 basement membrane 2 cell labeling 2 cell maturation 2 cell membrane 2 cell nucleus 2 cytoplasm 2 embryo 2 embryo development 2 epithelium cell 2 immunofluorescence 2 immunohistochemistry 2 immunoreactivity 2 larval stage 2 metamorphosis 2 nerve cell differentiation 2 nonhuman 2 olfactory bulb 2