Probe:	Flk-1 cDNA3
Probe preparation:	Antisense labelled with S35 RNA
Visualized with:	Autoradiography

Structure	Level	Pattern	Image	Note
TS12: head mesenchyme	Very strong	Spotted	4A/B
TS12: vitelline vein	Present		4A/B
TS12: heart	Present		4A/B	flk-1 transcripts were detectable in the endocardium.

Structure	Level	Pattern	Image	Note
TS12: blood island	Present	Spotted	4E/F	Expression was seen in yolk sac mesoderm in patches of cells lining the perimeter of the blood islands. Morphology of the cells indicate that expression is mainly confined to endothelial cell precursors.

Structure	Level	Pattern	Image	Note
TS18: liver	Present		4G/H
TS18: mesonephros	Present		4G/H
TS18: embryo	Present	Regionally restricted	4G/H	Expression was present in the meningeal plexus surrounding the spinal cord.
TS18: cardiovascular system	Present	Regionally restricted	4G/H	Expression was demonstrated in the endothelium of intervertebral vessels.

Structure	Level	Pattern	Image	Note
TS18: brain	Present	Regionally restricted		Expression was observed in the meninges of the developing brain.
TS18: umbilical artery extraembryonic part	Present
TS18: umbilical vein extraembryonic part	Present

Structure	Level	Pattern	Image	Note
TS20: brain	Present		4C/D
TS20: head mesenchyme	Present		4C/D
TS20: umbilical artery extraembryonic part	Present		4C/D
TS20: umbilical vein extraembryonic part	Present		4C/D
TS20: gut	Present		4C/D
TS20: lung	Present		4C/D
TS20: heart	Present	Regionally restricted	4C/D	Expression was observed in the endothelium.
TS20: cardiovascular system	Present	Regionally restricted	4C/D	Expression was seen in the intervertebral vessels.
TS20: embryo	Strong	Regionally restricted	4C/D	Expression was strong in the leptomeninges.

Structure	Level	Pattern	Image	Note
TS28: decidua	Present			Expression is present in the highly vascularized maternal decidual and labyrinthine layers.