Appearance of a mouse embryo inoculated with Ac-LDL-DiI at 10 dpc after 12 hours' whole-embryo culture. (A) An embryo before culture was inoculated with Ac-LDL-DiI into the heart. Arrow points out the injection needle. (B) An embryo after 12 hours' culture. (C-E) Vessel labeling after Ac-LDL-DiI staining 1 hour after inoculation observed under ultraviolet transillumination with the appropriate filter. (C) Region of the branchial arches. (D) Region of the heart. Note the delicate staining of the segmental arteries. (E) Truncal region. (F) magnified view of the upper part of the embryo.