Antibody:	anti-CD44 (IM7)
Detection system:	Secondary antibody coupled to horseradish peroxidase

Structure	Level	Pattern	Image	Note
TS12: allantois	Present		2A
TS12: amnion	Present		2A
TS12: heart	Present		2A
TS12: somite	Present		2A
TS12: cardiac muscle tissue	Strong	Regionally restricted	2A	High levels are expressed in the fused endothelial tubes and the surrounding muscular epimyocardium that constitute the early embryonic heart.
TS12: endocardial tube	Strong	Regionally restricted	2A	High levels are expressed in the fused endothelial tubes and the surrounding muscular epimyocardium that constitute the early embryonic heart.

Structure	Level	Pattern	Image	Note
TS15: heart	Present		2B
TS15: trunk somite	Present		2B
TS15: extraembryonic component	Present	Regionally restricted	2B	CD44 is expressed in the amnion and allantois.
TS15: branchial arch	Strong	Regionally restricted	2B	Strong staining is observed in the branchial clefts.
TS15: embryo	Strong	Regionally restricted	2B	Strong staining is observed in a population of cells dispersed through the embryo.
TS15: forelimb bud ectoderm	Strong	Regionally restricted	2B	At limb bud stage 1-2, CD44 protein is localized to the ectoderm on the ventral side of the limb bud. CD44 expression is not detected on the dorsal side.
TS15: embryo mesenchyme	Present	Scattered	2B	A large number of positive cells arise in the mesenchyme of the embryo, appearing as a scattered population first in the head region and then throughout the embryo.

Structure	Level	Pattern	Image	Note
TS15: endocardial lining	Weak		2C
TS15: cardiac muscle tissue	Present		2C	Expression is abundant in the developing myocardium.
TS15: arterial system	Strong	Regionally restricted	2C	The arterial system displays high CD44 protein expression. For example, CD44 protein is detected in the endothelial angioblasts lining the wall of the dorsal aortae.
TS15: dorsal aorta	Strong	Regionally restricted	2C	The arterial system displays high CD44 protein expression. For example, CD44 protein is detected in the endothelial angioblasts lining the wall of the dorsal aortae.
TS15: venous system	Absent		2C
TS15: embryo mesenchyme	Present	Regionally restricted	2C	A proportion of the CD44-positive cells can be seen in pathways suggestive of migratory neural crest.
TS15: migrating neural crest	Present	Regionally restricted	2C	A proportion of the CD44-positive cells can be seen in pathways suggestive of migratory neural crest.

Structure	Level	Pattern	Image	Note
TS17: heart	Present
TS17: endocardial cushion	Weak

Structure	Level	Pattern	Image	Note
TS20: arterial system	Strong

Structure	Level	Pattern	Image	Note
TS12: somite	Absent		3A

Structure	Level	Pattern	Image	Note
TS12: somite	Present	Regionally restricted	3B	Expression is observed in the most recently formed somites.
TS12: trunk unsegmented mesenchyme	Present		3B

Structure	Level	Pattern	Image	Note
TS13: trunk somite	Present	Graded	3C	The highest levels of expression are seen in the presomitic mesoderm and in the most posterior somites, with the levels of expression diminishing towards the anterior of the embryo and the most mature somites no longer expressing CD44.
TS13: trunk unsegmented mesenchyme	Present	Graded	3C	The highest levels of expression are seen in the presomitic mesoderm and in the most posterior somites, with the levels of expression diminishing towards the anterior of the embryo and the most mature somites no longer expressing CD44.

Structure	Level	Pattern	Image	Note
TS13: trunk somite	Present	Regionally restricted	3D	During maturation, the protein associates with the sclerotome in the central regions of the positive somites and the outer somitic regions are CD44-negative.

Structure	Level	Pattern	Image	Note
TS17: arterial system	Strong		3E	The arterial system displays high CD44 protein expression. For example, CD44 protein is detected in the intersomitic arteries.

Structure	Level	Pattern	Image	Note
TS17: notochord	Strong	Regionally restricted	3F	The notochord in the tail expresses high levels of CD44 protein.
TS17: tail	Present	Regionally restricted	3F	Expression was detected in a patch of cells on the ventral aspect of the tailbud.
TS17: tail mesenchyme	Present	Scattered	3F	A large number of positive cells arise in the mesenchyme of the embryo, appearing as a scattered population throughout the embryo including the tail.

Structure	Level	Pattern	Image	Note
TS17: notochord	Strong	Regionally restricted	3G	The notochord in the tail expresses high levels of CD44 protein.

Structure	Level	Pattern	Image	Note
TS15: forelimb bud ectoderm	Strong	Regionally restricted	4A	At limb bud stage 1-2, CD44 protein is localized to the ectoderm on the ventral side of the limb bud. CD44 expression is not detected on the dorsal side.

Structure	Level	Pattern	Image	Note
TS15: forelimb bud ectoderm	Strong	Regionally restricted	4B	At limb bud stage 1-2, CD44 protein is localized to the ectoderm on the ventral side of the limb bud. CD44 expression is not detected on the dorsal side.

Structure	Level	Pattern	Image	Note
TS17: hindlimb bud apical ectodermal ridge	Present		4C	limb bud stage 2-3

Structure	Level	Pattern	Image	Note
TS17: hindlimb bud apical ectodermal ridge	Present		4D	limb bud stage 2-3

Structure	Level	Pattern	Image	Note
TS17: forelimb bud apical ectodermal ridge	Present		4E	limb bud stage 4
TS17: forelimb bud mesenchyme	Present	Scattered	4E	A large number of positive cells arise in the mesenchyme of the embryo, appearing as a scattered population throughout the embryo including the limb buds.

Structure	Level	Pattern	Image	Note
TS20: hindlimb	Present	Regionally restricted	4F	At limb bud stage 8, expression in the AER is maintained, but CD44 is also expressed in the condensing limb-bud mesenchyme prior to the cartilage-generating chondrogenic process.

Structure	Level	Pattern	Image	Note
TS13: 1st branchial pouch endoderm	Present	Regionally restricted		CD44 protein first appears in the branchial arch region as a patch in the endoderm of the developing first pharyngeal pouch adjacent to the developing first branchial arch.

Structure	Level	Pattern	Image	Note
TS15: arterial system	Strong	Regionally restricted	5A	The arterial system displays high CD44 protein expression. For example, CD44 protein is detected in the endothelial angioblasts lining the wall of the dorsal aortae.
TS15: dorsal aorta	Strong	Regionally restricted	5A	The arterial system displays high CD44 protein expression. For example, CD44 protein is detected in the endothelial angioblasts lining the wall of the dorsal aortae.
TS15: 1st branchial groove	Present		5A
TS15: 2nd branchial groove	Present		5A

Structure	Level	Pattern	Image	Note
TS15: 1st branchial pouch endoderm	Strong		5D , 5E
TS15: 1st branchial membrane endoderm	Present		5E , 5D
TS15: 2nd branchial arch ectoderm	Weak		5D , 5E
TS15: branchial arch mesenchyme	Absent		5E , 5D

Structure	Level	Pattern	Image	Note
TS17: 1st branchial pouch endoderm	Present		5G , 5F
TS17: 2nd branchial arch ectoderm	Present	Regionally restricted	5F , 5G	CD44 protein is localized to the ectoderm around the posterior side of the second branchial arch.
TS17: branchial pouch endoderm	Present		5G , 5F	Expression is localized to the endoderm surrounding all pharyngeal pouches.
TS17: embryo mesenchyme	Present	Scattered	5G , 5F	A large number of positive cells arise in the mesenchyme of the embryo, appearing as a scattered population. Some of these cells have a stellate morphology and many have cytoplasmic CD44.

Structure	Level	Pattern	Image	Note
TS17: 2nd branchial pouch endoderm	Present		5I , 5H
TS17: branchial pouch	Present		5I , 5H	Expression is localized to the endoderm surrounding all pharyngeal pouches.
TS17: 3rd branchial arch ectoderm	Present		5I , 5H	CD44 protein is localized to the ectoderm surrounding the third and fourth arches.
TS17: 4th branchial arch ectoderm	Present		5I , 5H	CD44 protein is localized to the ectoderm surrounding the third and fourth arches.
TS17: branchial arch artery	Strong	Regionally restricted	5I	The arterial system displays high CD44 protein expression. CD44 is observed in the cells lining the branchial arch arteries.
TS17: blood	Present		5I	Some blood cells present in the branchial arch arteries express CD44.
TS17: embryo mesenchyme	Present	Scattered	5H , 5I	A large number of positive cells arise in the mesenchyme of the embryo, appearing as a scattered population. Some of these cells have a stellate morphology and many have cytoplasmic CD44.

Structure	Level	Pattern	Image	Note
TS17: naso-lacrimal groove	Present	Regionally restricted	6A	CD44 is expressed in the ectoderm of the nasolacrimal groove.
TS17: heart	Present		6A
TS17: embryo mesenchyme	Present	Scattered	6A	A large number of positive cells arise in the mesenchyme of the embryo, appearing as a scattered population throughout the embryo including the limb buds and tail.

Structure	Level	Pattern	Image	Note
TS17: branchial arch artery	Strong	Regionally restricted	6C	The arterial system displays high CD44 protein expression. CD44 is observed in the cells lining the branchial arch arteries.
TS17: nasal pit	Present	Regionally restricted	6C	CD44 is expressed in the posterolateral rim of the developing nasal pit.

Structure	Level	Pattern	Image	Note
TS17: 1st branchial arch mandibular component	Present	Regionally restricted	6D	CD44 expression is observed in the odontogenic placodes.
TS17: 1st branchial arch maxillary component	Present	Regionally restricted	6D	CD44 expression is observed in the odontogenic placodes.

Structure	Level	Pattern	Image	Note
TS15: head	Present	Regionally restricted	7A	CD44-positive cells were present subectodermally in the region of the forebrain.
TS15: head mesenchyme	Present	Regionally restricted	7A	Positive cells were dispersed deep with the mesenchyme.
TS15: future hindbrain roof plate	Present		7A

Structure	Level	Pattern	Image	Note
TS17: forebrain	Present	Regionally restricted	7B
TS17: hindbrain	Present	Regionally restricted	7B

Structure	Level	Pattern	Image	Note
TS17: liver	Present		7C

Structure	Level	Pattern	Image	Note
TS17: yolk sac visceral endoderm	Present		7E , 7D