Fig. 1. Expression of Sema5A mRNA. (A) Sema5A in situ hybridization in the E14 mouse retinal pathway. Sema5A was expressed at the optic disc and along the developing optic nerve to the ventral diencephalon. The boxed areas are shown at higher magnification in B and E. (B) Sema5A mRNA expression at the optic disc. Hybridization signal using an antisense probe was present in neuroepithelial cells that flank the exiting retinal axons (^*). As a group, these Sema5A-positive neuroepithelial cells formed a collar around the retinal axon bundle. (C) Hybridization at the optic disc using the Sema5A sense probe. (D) Hybridization at the optic disc using the Sema5B probe showed no signal. (E) Sema5A mRNA expression in the developing optic nerve. Note the presence of hybridization signal in neuroepithelial cells flanking the central core containing retinal axons. (F) Hybridization in the optic nerve using the Sema5A sense probe. (G) Sema5A mRNA expression in the lamina propria (LP) under the olfactory epithelium (OE). Scale bars: (A) 150 µm; (B-F) 25 µm; (G) 75 µm.