Antibody:	anti-HOXA5
Detection system:	Secondary antibody coupled to Alexa Fluor 488

Structure	Level	Pattern	Image	Note
TS22: brown fat	Strong	Widespread	1A	Highly expressed throughout brown adipose tissue (BAT) when it first becomes morphologically identifiable at E14.5.

Structure	Cell Type	Level	Pattern	Image	Note
TS22: brown fat	brown adipocyte	Present		1D , 1B	Expression in adipocyte nuclei, colocalized with Ebf2 expression.

Structure	Level	Pattern	Image	Note
TS24: brown fat	Strong	Regionally restricted	1E	Expression continued to be high in scapular BAT at E16.5.

Structure	Cell Type	Level	Pattern	Image	Note
TS24: brown fat	brown adipocyte	Present	Regionally restricted	1F , 1G	Expression in nuclei of round adipocytes.
TS24: brown fat	fibroblast	Present	Regionally restricted	1G , 1F	Expression in sickle-shaped connective tissue fibroblasts within BAT.

Structure	Cell Type	Level	Pattern	Image	Note
TS24: brown fat	fibroblast	Present	Regionally restricted	1G inset	Expression in BAT fibroblasts, co-expressed with Pdgfra.

Structure	Level	Pattern	Image	Note
TS26: brown fat	Absent			Expression in BAT decreased; not detected by immunofluorescence.

Structure	Level	Pattern	Image	Note
TS20: trunk mesenchyme	Present	Regionally restricted	2B , 2D	Expression in mesenchyme, mostly somite derived, flanking myotome extending laterally to scapula and medially to neural tube, colocalized with Ebf2 expression.

Structure	Cell Type	Level	Pattern	Image	Note
TS20: trunk mesenchyme		Present	Regionally restricted	2E , 2H , 2F	Expression in mesenchyme flanking epaxial myotome, colocalized with Ebf2 expression.
TS20: myotome	skeletal muscle fibroblast	Present	Regionally restricted	2F , 2E , 2H	Expression in prospective muscle connective tissue fibroblasts interspersed within myotome.
TS20: skeletal muscle		Absent		2E , 2H , 2F	No expression in epaxial muscle mass.

Structure	Level	Pattern	Image	Note
TS20: trunk mesenchyme	Present	Regionally restricted	2I	Expression in mesenchyme lateral to epaxial myotome, colocalized with Prdm16 expression.

Structure	Cell Type	Level	Pattern	Image	Note
TS20: myotome	skeletal muscle fibroblast	Present	Regionally restricted	2J , 2L	Expression in prospective muscle connective tissue fibroblasts within myotome.

Structure	Level	Pattern	Image	Note
TS24: trunk connective tissue	Present	Regionally restricted	S4B , S4A

Structure	Cell Type	Level	Pattern	Image	Note
TS24: brown fat	brown adipocyte	Present		S4D , S4C	Expression in all adipocytes and in connective tissue fibroblasts.
TS24: brown fat	fibroblast	Present		S4D , S4C	Expression in all adipocytes and in connective tissue fibroblasts.

Structure	Cell Type	Level	Pattern	Image	Note
TS24: skeletal muscle	skeletal muscle fibroblast	Present	Regionally restricted	S4F , S4E	Expression in epaxial muscle.

Structure	Cell Type	Level	Pattern	Image	Note
TS24: trachea	tracheobronchial chondrocyte	Strong	Regionally restricted	S4G

Structure	Level	Pattern	Image	Note
TS24: trunk connective tissue	Present	Regionally restricted	S4H , S4I

Structure	Cell Type	Level	Pattern	Image	Note
TS24: brown fat	brown adipocyte	Absent		S4J , S4K
TS24: brown fat	fibroblast	Present	Regionally restricted	S4K , S4J	Expression in some but not all connective tissue fibroblasts.

Structure	Cell Type	Level	Pattern	Image	Note
TS24: skeletal muscle	skeletal muscle fibroblast	Present		S4M , S4L

Structure	Cell Type	Level	Pattern	Image	Note
TS24: trachea	tracheobronchial chondrocyte	Strong	Regionally restricted	S4N	Abundant nuclear expression in tracheal chondrocytes.

Structure	Level	Pattern	Image	Note
TS24: brown fat	Absent		S4P

Structure	Level	Pattern	Image	Note
TS24: skeletal muscle	Absent		S4Q , S4R

Structure	Level	Pattern	Image	Note
TS24: trachea	Absent		S4S

Structure	Level	Pattern	Image	Note
TS24: trunk connective tissue	Present	Regionally restricted	S4T , S4U

Structure	Cell Type	Level	Pattern	Image	Note
TS24: brown fat	brown adipocyte	Trace	Scattered	S4V , S4X	Single expressing adipocyte in field of view shown.
TS24: brown fat	fibroblast	Present	Regionally restricted	S4X , S4V	Expression in elongated cells that are either fibroblasts or endothelial cells.

Structure	Cell Type	Level	Pattern	Image	Note
TS24: skeletal muscle	skeletal muscle fibroblast	Present	Regionally restricted	S4Y , S4AA	Expression in epaxial muscle.

Structure	Cell Type	Level	Pattern	Image	Note
TS24: trachea	tracheobronchial chondrocyte	Present		S4AB