Antibody:	MEC 13.3
Detection system:	horseradish peroxidase

Structure	Level	Pattern	Image	Note
TS13: embryo	Present	Regionally restricted	3A	PECAM-1-positive cells were not present in the anterior part of the mutant embryo. No staining could ever be detected rostrally to the cardiac region.
TS13: sinus venosus	Present		3A

Structure	Level	Pattern	Image	Note
TS13: posterior cardinal vein	Absent		3B
TS13: dorsal aorta	Present		3B	Dorsal aortae in the caudal region were visible but appeared incompletely formed.
TS13: embryo	Present	Regionally restricted	3B	No staining could ever be detected rostrally to the cardiac region.

Structure	Level	Pattern	Image	Note
TS13: dorsal aorta	Present		3C
TS13: posterior cardinal vein	Present		3C
TS13: sinus venosus	Present		3C
TS13: cardiovascular system	Present		3C	In normal embryos, angioblasts amalgamated to form nearly continuous structures and vascular network was obvious in the first aortic arch and in the head mesenchyme.

Structure	Level	Pattern	Image	Note
TS14: cardiovascular system	Present		4A	Vascular deficiencies of mutant embryos were more pronounced and included the presence of a delicate plexus rather than organized large vessels.
TS14: extraembryonic vascular system	Present		4A	Instead of forming a dense vascular network, angioglasts in the allantois aggregated and constituted a collection of islets.

Structure	Level	Pattern	Image	Note
TS14: cardiovascular system	Present		4B
TS14: extraembryonic vascular system	Present		4B