Fig. 1. Lateral and anteroposterior (AP) migration of MEE seam cells during in vitro palate fusion. (A,D) Diagrams showing the [Rosa26C57BL/6] chimeric pair culture of palate and the section positions for panels (B,C,E), as indicated by the lines. (B) Cross section through the middle region of a [Rosa26C57BL/6] chimeric palate pair. The palate shelves were dissected from E14.0 mouse embryos and cultured oral side up for18 hours then stained for ß-gal. ß-gal-positive cells (blue) are present in the nasal epithelium region of the C57BL/6 half of the pair (arrowhead). (C) Cross section through the posterior region of the [Rosa26C57BL/6] chimeric palate pair shown in B. A low number of ß-gal-positive cells (blue) were detected in the medial edge epithelium region of the C57BL/6 half of the pair (arrowhead), even though the two palate shelves were still separated in this posterior region. (E) A [Rosa26C57BL/6] chimeric palate pair from an E14.0 mouse embryo cultured for 18 hours and then stained with ß-gal and sectioned as indicated in D. Note the extension of the ß-gal-positive cells (blue) from the middle joint region (arrow) to the posterior separated region (arrowhead). Scale bars: 50 µm.