Antibody:

anti-PRRX1

Structure	Level	Pattern	Image	Note
TS15: mesenchyme derived from lateral plate	Present	Widespread	1A' , 1A	Most mesenchymal cells are positive for expression.
TS15: forelimb bud mesenchyme	Strong	Widespread	1A' , 1A	Peak expression in limb bud around E9-10. Expression thoughout mesenchyme.

Structure	Level	Pattern	Image	Note
TS17: forelimb bud mesenchyme	Present	Regionally restricted	1B' , 1B	Expression downregulated in mesenchymal cells in midline of limb.

Structure	Level	Pattern	Image	Note
TS20: forelimb mesenchyme	Present	Widespread	1C , 1C'	Expression in most mesenchymal cells.
TS20: limb cartilage condensation	Weak	Regionally restricted	1C , 1C'	Expression downregulated in Sox9-expressing cartilage condensations

Structure	Level	Pattern	Image	Note
TS24: forelimb mesenchyme	Present	Regionally restricted	1D' , 1D	Clear zones of expression. Expression in most connective tissue cells.
TS24: elbow mesenchyme	Strong		1D , 1D'	Expression highest in elbow area.

Structure	Level	Pattern	Image	Note
TS27: dermis	Strong	Widespread	1E	Abundant expression across dermis, including reticular and papillary dermis.
TS27: dermis papillary layer	Present		1E
TS27: dermis reticular layer	Present		1E
TS27: epidermis	Absent		1E

Structure	Level	Pattern	Image	Note
TS28: dermis	Present	Regionally restricted	1F , 1F'	Expression overlapping with Pdgfra reporter expression.

Structure	Level	Pattern	Image	Note
TS28: dermis	Present	Regionally restricted	1G	Expression in 22.8% of Pdgfra reporter-expressing cells.