Fig. 1. COUP-TFs are expressed in migrating cells. Adjacent coronal sections of an E13.5 mouse brain at a medio-caudal level immunostained with anti-COUP-TFI (A) and COUP-TFII antibodies (A'). The asterisks in A and A' indicate expression in the interganglionic region (the `MLGE'). The insets show an enlargement of this region after double labelling of COUP-TFs (COUP-TFI mRNA/COUP-TFII antibody in A; COUP-TFI antibody/COUP-TFII mRNA in A'). The arrow in A indicates the expression boundary of COUP-TFI at the level of the medial cortex, whereas in the same region COUP-TFII is expressed in the putative cortical hem region (ch in A'). An arrow in A' indicates expression in the marginal zone of the ncx, and the arrowheads show expression at the cortico-striatal boundary and in the intermediate zone of the ncx. (B-B''') Two different enlargements of the regions indicated in A and A'. Most COUP-TF-positive cells show a polarized soma (arrows in B-B'''), indicative of migrating cells. (C-C') Expression of COUP-TFs in the POa region. Note that COUP-TFI is mostly restricted in the ventricular zone and in two streams of migrating cells, as indicated by the arrows. High expression of COUP-TFII is mainly localized in the mantle zone and in a dorsally migrating stream (arrow in C'). ch, cortical hem region; cp, choroid plexus; LGE, lateral ganglionic eminence; MGE, medial ganglionic eminence; mz, mantle zone; ncx, neocortex; pcx, piriform cortex; POa, pre-optic area; VZ, ventricular zone.