FIG. 4.

The expanded domain of GFP fluorescence within the telencephalon of Tg(Eomes::GFP) embryos is due to perdurance of GFP protein. (a) Brightfield and GFP overlay of vibratome sections of E14.5 brains illustrating GFP localization. (b,c) GFP expression by in situ hybridization (b) reveals that GFP transcript has a more restricted expression domain that appears to be identical to the expression of Eomes transcripts (c). High magnification insets depict the localization of GFP and Eomes transcripts largely within the subventricular and intermediate zones. (d) By postnatal day 0 (P0), GFP fluorescence is reduced to regions of the olfactory bulb (not shown) and the hippocampus. High magnification inset illustrates relatively restricted domain of GFP fluorescence. (e,f) In situ hybridization reveals that both GFP and Eomes expression is localized to identical regions of the hippocampus and is complementary with observed GFP fluorescence (d). High magnification insets depicting expression of GFP and Eomes in early postnatal hippocampus. (g,h) In situ hybridization depicting Eomes transcript localization at the base of the developing digit IV (g) in a ring of cells surrounding the fourth condensation (h). (i,l) GFP fluorescence is also localized to the base of digit IV and correlates closely with endogenous Eomes expression. (k–n) High magnification confocal images depicting the ring of GFP expression (m) around a more densely populated condensation. Scale bars = 100 μm. nctx, neocortex; lge, lateral ganglionic eminence; mge, medial ganglionic eminence; ctx, cortex; hp, hippocampus; DG, dentate gyrus; th, thalamus; hy, hypothalamus.