Figure 3. N1⁴⁵⁷-nGFP directs GFP expression precisely to the Neurog1 lineage.

(A,B) show a cross section through the neural tube of an E11.5 N1⁴⁵⁷-nGFP embryo labeled by immunoflorescence for Neurog1 (A) or direct fluorescence of GFP (B) and indicate GFP expression is restricted to Neurog1 domains in the dnt, vnt, and drg at this level. Arrows indicate the dorsal and ventral boundaries of expression for Neurog1 and GFP match. (C,D) are high magnification of views of the dnt and vnt demonstrating the co-expression of Neurog1 and GFP. (E-I) focuses on the dnt and compares GFP with immunofluorescence for Neurog1, Ascl1, Atoh1, Lhx1/5 or Lhx2/9 from N1⁴⁵⁷-nGFP in E11.5 dnt. Overlap of the GFP signal with Neurog1 (yellow) and Lhx1/5 (turquoise) but none of the other factors illustrates the precision with which the BAC transgene is controlling GFP expression. (J-O) focuses on the vnt and compares GFP with immunofluorescence for Neurog1, Ascl1, Olig2, Lhx1/5, Brn3a, Chx10 and Isl1 from N1⁴⁵⁷-nGFP in E11.5 vnt. Dashed line indicates position of the ventricular zone. Overlap of the GFP signal with Neurog1 (yellow), Lhx1/5 (turquoise), and Chox10 (yellow) but none of the other factors suggests the Neurog1 lineage in the ventral neural tube comprises interneurons rather than motoneurons. Diagrams for progenitor/neuron relationships and markers are shown for both dnt and vnt. dI5 and dI6, dorsal interneurons 5 and 6; MN, motoneuron; V0-V2, ventral interneurons.