MARCKS and F-actin distribution during the formation of the lens vesicle. Stage 15 chick embryo cryosection, at the head level, showing the optic cup (oc) and lens placode (l). Double labeling of MARCKS, using a polyclonal antibody, and actin filaments, using phalloidin. d, diencephalon; ec, ectoderm; l, closing lens placode; m, head mesenchyme; oc, optic cup. Scale bar: 60 μm.