HSC localization. (A) Transverse cryosection of an E11 Ly-6A GFP⁺ embryo (GFP in green) costained for the endothelial marker CD34 (red, Cy5; mounted with Vectashield; Vector Laboratories) showing the dorsal aorta with intra-aortic clusters marked by asterisks and the joining vitelline artery indicated by a white arrow. Ventral, down. DA indicates dorsal aorta; and VA, vitelline artery. Pictures were taken on a Zeiss LSM510NLO/FCS confocal microscope with a 40×/1.3 NA objective and images were analyzed with Zeiss LSM image software (both from Carl Zeiss BV). (B) Subdissection of an embryonic day (E) 11 dorsal aorta. Ventral, left; rostral, top. r indicates rostral; m, middle; and c, caudal. Aortae were dissected under a Nikon SMZ800 dissection microscope (Nikon), pictures were taken with a Pixera Pro 150ES camera (Pixera), and images were analyzed with the Pixera Viewfinder software (Pixera). (C) Percentage of mice reconstituted with the different parts of the E11 dorsal aorta (rostral and caudal parts pooled) after transplantation into irradiated mice. The number of pooled, transplanted tissues (ie, m or r + c) is indicated as embryo equivalent (ee) and the number of repopulated mice/number of mice injected is indicated for each bar.