MARCKS and F-actin distribution in the open neural plate. Stage 6 chick embryo transverse cryosection, at the presumptive cephalic region. Double labeling of MARCKS, using a polyclonal antibody, and actin filaments, using phalloidin. In order to show all the neural plate and the adjacent ectoderm, these pictures were reconstructed from five consecutive microscopic fields photographied for each fluorochrome. ec, non-neural ectoderm; m, mesoderm; np, neural plate. Scale bar: 120 μm.