(Downloading may take up to 30 seconds.
If the slide opens in your browser, select File -> Save As to save it.)
Click on image to view larger version.

Fig. 5. Formation of the aorta and molecular characterization of somite
angioblasts. (A-E) Cross-sections from caudal (A) to cephalic (E) levels
in an 18-somite quail embryo. QH1 staining merged to Nomarski's interferential
contrast. (A) Primitive streak level. QH1+ angioblasts
visible at a lateral position (arrowhead) aggregate against the endoderm and
organize into groups of cells. (B) Segmental plate level.
QH1+ groups organize into vessels that progressively fuse. These
structures remain positioned lateral to the segmental plate. (C)
Nascent somite level. The paired aortae have formed. A few QH1+
angioblasts are now detected in a dorsal position. (D) Epithelialized
somite level. The paired aortae are now underneath the somites. Dorsal
QH1+ angioblasts become more numerous. (E) Dermomyotome and
sclerotome have separated. Conspicuous QH1+ cells are around the
Wolffian duct (arrow) and in close association with the aortic roof
(arrowhead). Scale bar: 100 µm. (F-I). EC-specific markers in chick
(F-H) and quail (I) somites. (F-H) GATA2, VEGFR2 and SCL/TAL1 in situ
hybridization. All markers delineate a quadrant of cells in the dorsolateral
aspect of the epithelial somite (arrow). GATA2 is also present in the
epidermis (Sheng and Stern,
1999; Minko et al.,
2003). (I) QH1 immunohistochemistry. Scale bar: 50 µm. D,
dermomyotome; E, ectoderm; En, endoderm; M, mesoderm; Sc, sclerotome; So,
somatopleural mesoderm; Sp, splanchnopleural mesoderm; SP, segmental plate;
WD, Wolffian duct.