Ptch1 transcripts are present in periocular mesenchyme and the neural retina throughout eye morphogenesis and into post-natal life. (A) On embryonic day (E)9.5 in transverse mouse embryo sections, antisense riboprobes labeled with digoxygenin demonstrate Ptch1 expression in cephalic mesectoderm of neural crest origin in the head (arrow) and maxillary arch (Mx); in the basal diencephalon (Di) and basal neural tube at trunk levels, and in the somitic sclerotome (S) and basal spinal cord. Ectodermal expression is constant at all embryonic stages examined (Ec). By E11.5, the distal diencephalic infundibulum transcribes Ptch1 (data not shown) as does the subectodermal mesenchyme of the future eyelids and palate. (C) Mesenchymal Ptch1 expression continues at E13.5, particularly in the superior and inferior palpebrae (eyelids; sPa, iPa); the lateral neural retina (Re) and differentiated outer cells of the lens (Le) begin to also transcribe Ptch1, which continues throughout these structures at E15.5 (inset). By this stage, initially generalized expression in the developing cornea has become restricted to the epithelium (Co, boxes in C/inset/D). (E) In adult mouse eyes on post-natal day 50, transcripts are found within the outer and inner nuclear layers (Onl, Inl), corresponding to photoreceptor and Müller cell bodies, and within the retinal ganglion cell layer (Rgc), testifying to a post-natal role in retinal maintenance. Transcripts not observed within the stroma of the anterior chamber or the sclera (Scl). (F) Rpe, retinal pigmented epithelium; Cp; choroid plexus. Scale bar A–D, 400 µm; E, F, 200 µm. Hybridization with a sense-oriented Ptch1 probe as negative control in B, D, F.
