Effects of Gata6 carboxyl zinc-finger deletion in the developing
mouse AV conduction system. In situ hybridization with probes against
Gata6-exon4, Tbx3 and Id2 mRNA in frontal
sections from Mlc2v-CreGata6f/f mouse embryos are
shown. In the absence of Gata6 with a carboxyl zinc-finger,
Gata6 expression at E12.5 (A) overlaps with that of
Tbx3 (D) and Id2 (G), but the region
stained by each of these transcripts is smaller compared to similar anatomic
sections from hearts with intact Gata6. A reduced area stained
by Gata6 (B), Tbx3 (E) and
Id2 (H) persists at E14.5, as well at E16.5 (C, F & I).
The white arrows point to regions of the developing CCS that are either marked
or devoid of Gata6+ staining. The yellow arrowheads point to
regions of positive signal within the developing AV node and AV bundle. The
white arrowheads point to regions of positive signal within the developing
bundle branches. Scale bar=100 μm. Scale bar in (A) applies to all E12.5
images; scale bar in (B) applies to all E14.5 images; scale bar in (C) applies
to all E16.5 images.