Figure 1.

Branched animal organs. (A) Drosophila embryonic tracheal system stained with the tracheal luminal antigen mAb2A12, reproduced with permission from Development (Samakovlis et al. 1996a) (http://dev.biologists.org/content/122/5/1395). (B) Three-day-old zebrafish embryo vascular system expressing EGFP under the control of the endothelial specific promoter of the flk1 gene (TG:flk1:EGFP). (C) Developing mouse kidney stained for Wilm’s tumor 1 antigen (red, developing glomeruli) and calbindin (green, ureteric tree). (Photo courtesy of Kenneth Walker and John Bertram.) (D) Mammary gland of a virgin rat (Schedin et al. 2007). (From Schedin et al. 2007; adapted, with kind permission, from Springer Science+Business Media, J Mammary Gland Biol Neoplasia © 2007.) (E) Whole mount of an embryonic day 14.5 (E14.5) mouse lung stained for E-cadherin to show the airway epithelium. (Photo courtesy of Ross J. Metzger.) (F) Two-photon fluorescence image of Purkinje cell filled with a fluorescent dye. (Photo courtesy of Yo Otsu and Stéphane Dieudonné.)