Figure 3.

Fgf8 genetic lineage cell fate tracing. A–E, Parasagittal (A–C) and coronal (D, E) sections of E11.5 Fgf8Cre/RosaYFP embryos. A, Yellow fluorescent protein (YFP) immunostaining (brown) reveals Fgf8 lineage (YFP expression) in the facial epidermis (Ep) and along the rostral RE. YFP expression was not detected in the OE and VNO, confirming distinct genetic lineage for the Fgf8-expressing epidermis and these structures. B–C, YFP (green) and tubulin+HuCD immunostaining (red). Neurons (red) of the OE (B) and VNO (C) derive from progenitors negative for Fgf8 expression (green). D, Section shows the distinct lineage for neuronal cells of OE, VNO, and migratory mass (MM; red only) and the Fgf8 (YFP+)-expressing epidermal cells (green). Fgf8 lineage was found for the superficial ectoderm forming the epidermis (Ep) along the lateral (LNP) and medial nasal process (MNP). Note that neurons positive for Fgf8 lineage were detected in the developing forebrain (arrowheads, Br). E, Immunostaining against YFP (brown) and tubulin III (gray-blue); use boxed area in F as reference. No neuronal Fgf8 lineage was detected in the lateral or medial neuroepithelium. F–I, E15.5 Fgf8Cre/RosaYFP embryo. F, YFP expression (brown) was detected in the facial epidermis (Ep), rostral RE, and oral mucosa (OM), but not in the OE and VNO. YFP (green) and tubulin+HuCD immunostaining (red) confirmed lack of Fgf8 lineage in the OE (G) and VNO (H). I, YFP expression (brown) was detected in the oral mucosa (OM) and dental enamel (TE), but not the tongue (Tng). Scale bars: A, D, F, I, 100 μm; B, C, E, G, H, 50 μm.