Fig. 4. Conservation of node monocilia. mRNA encoding endogenous left-right dynein (LRD), a protein involved in node monocilia in the mouse, is seen in Hensen's node in the chick, dorsal blastopore cells of the early neurula stage Xenopus, and the zebrafish shield (A,D,G,J; arrows). Monocilia are revealed on the apical surfaces of mouse ventral node cells and in cells of the related structures in chick, Xenopus and zebrafish embryos by immunostaining with anti-acetylated tubulin (B,E,H,K; arrows); a schematic representation is also shown (C,F,I,L). Reproduced, with permission, from the Nature Publishing Group (http://www.nature.com) (Essner et al., 2002).