Fig. 1.

Scanning electron analyses of the posterior ventral diencephalon in E10.5 Sox2^CONT and Sox2^HYP embryos. (A–C) Posterior-facing views of Sox2^CONT (A) and Sox2^HYP (B and C) E10.5 diencephala. Scale bars for A–C: 100 μm. (D–F) Magnified images of the regions outlined in blue in (A-C) showing the mammillary region, tuberal hypothalamus, and infundibulum of Sox2^CONT (D) and Sox2^HYP (E and F) embryos. Sox2^CONT mammillary pouches appear as singular midline invaginations. (D) In contrast, Sox2^HYP mammillary pouches are often divided by ectopic, undescended tissue (arrow in E). The infundibula of Sox2^HYP embryos are expanded relative to those of Sox2^CONT embryos (D vs. E, F, red asterisks). A subset of Sox2^HYP embryos exhibit a protuberance in the tuberal hypothalamus by E10.5 (arrowhead). Scale bars for D–F: 50 μm. MP: mammillary pouch; TH: tuberal hypothalamus; I: infundibulum.