Localization of RhoA and RhoB immunoreactive proteins to explanted neural primordia. (A,B) RhoA (SC418) is expressed in the neural tube (NT) and in the adjacent flattening epithelioid sheet (Ep) but is downregulated in mesenchymal (M) NC cells. (A) Phase contrast; (A') RhoA; (B) higher magnification of the inset in (A') showing a membrane-associated pattern (arrows) that progressively disappears from cells about to delaminate (arrowheads) until full downregulation in mesenchymal progenitors. (C,D) RhoB (SC180) is expressed in the NT, in the epithelioid sheet and in mesenchymal NC cells. (C) Phase contrast; (C') RhoB; (D) higher magnification of the inset in (C') showing both membrane-associated RhoB (arrows), which disappears from cells about to delaminate (arrowheads), and a cytoplasmic staining that is kept in the mesenchymal cells (M, inset). Insets in (B,D) show expression of a GFP variant following electroporation that associates with the surface membrane (green). Note yellow staining reflecting colocalization with RhoA or RhoB. Bar: 22 μM (A,A',C,C'); 5 μM (B,D) and insets; 3.5 μM, lower inset in (D).