Figure 2.
Ngns down-regulate Mash1 transcription in the dorsal telencephalon. (A,B) Distribution of Ngn1 transcripts on frontal sections of E12.5 wild-type (A) and Ngn2 mutant (B) forebrain. Ngn1 expression is dependent on Ngn2 function in dorsal and medial cortical domains (arrowhead, B) and independent of Ngn2 in a lateral cortical domain. (C,D) Distribution of Ngn2 transcripts on frontal sections of E12.5 wild-type (C) and Ngn1 mutant (D) forebrain. Ngn2 is expressed at reduced levels in cortical progenitors of Ngn1 mutants, suggesting that Ngn2 transcription is partially dependent on Ngn1 function throughout the dorsal telencephalon. (E,J) Distribution of Mash1 transcripts on frontal sections of E12.5 wild-type (E), Ngn1 mutant (G), Ngn2 mutant (G), and Ngn1; Ngn2 double mutant (H), and of E13.5 wild-type (I) and Ngn2 mutant (J) forebrain. Mash1 expression is up-regulated in the VZ of the dorsal telencephalon (arrowhead in Fand H) and dorsal thalamus of Ngn2 single and more strikingly of Ngn1;Ngn2 double mutant embryos.