Fig. 4. Clonal analysis of the migration of Grg4-expressing cells. (A) Electroporation with RCAS-AP on virus-resistant embryos at E2 that were fixed at E8. (Left column) AP immunocytochemistry. (Right column) Number of AP-positive cells in each lamina. (B) Electroporation with RCAS-Grg4 on virus-resistant embryos at E2 that were fixed at E8. (Left column) In situ hybridization for Grg4. (Right column) Number of Grg4-expressing cells in each lamina. In virus-resistant embryos, misexpression is limited to the descendents of originally transfected cells. AP-positive cells are present throughout all laminae (A), but Grg4-expressing cells are found mainly in lamina IId (B). Scale bars: 100 µm.