Figure 2
Depletion of ventral telencephalic Pax6 using the Six3A1A2- Cre allele. (A, D) The Z/AP allele was used to reveal sites of Cre activity at E12.5 and E14.5 by expression of human placental alkaline phosphatase (hPLAP). Cre activity was restricted to bilateral patches in the ventral telencephalon (for example, white arrowhead in (A): note that brown stain elsewhere in lines of cells running throughout the tissue and along the pial surface is alkaline phosphatase reactivity in blood vessels). (B, C, E) Immunohistochemistry for Pax6 expression in the ventral telencephalon of normal embryos aged E12.5 and E14.5; the section in (B) is rostral to that in (C); the white arrowhead in (B) indicates a cluster of Pax6-expressing cells in the ventral medial ganglionic eminence (MGE) in a similar position to the hPLAP staining marked by the white arrowhead in (A); the section in (E) is of the same region as that shown in (D). Broken lines in (D, E) mark the internal capsule's ventral edge. (F, G) Immunohistochemistry for Pax6 expression in the region indicated by the white arrowhead in (B) in control and conditional knockout (cKO) embryos at E12.5; quantification of the reduced density of Pax6-expressing cells in this region is shown in (H). (I, J) Immunohistochemistry for expression of Pax6 in the region shown in (D, E) in control and cKO embryos at E14.5; quantification of the reduced density of Pax6-expressing cells in this region is shown in (K). Abbreviations: Cx, cortex; IC, internal capsule; LCS, lateral cortical stream; LGE, lateral ganglionic eminence. Scale bars: 50 μm.