Antibody:	Anti-Hoxb5
Detection system:	Biotinylated secondary antibody/[Strept]avidin coupled to alkaline phosphatase

Structure	Level	Pattern	Image	Note
TS21: lung mesenchyme	Present		1B	Staining was noted in most mesenchymal cell nuclei.
TS21: lung epithelium	Absent		1B	No staining was seen in adjacent columnar epithelial cells.
TS21: trachea epithelium	Absent		1B

Structure	Level	Pattern	Image	Note
TS22: lung	Present	Regionally restricted	1C	Immunostaining was seen in nuclei of both subepithelial fibroblasts and adjacent columnar epithelial cells of early airways.
TS22: lung epithelium	Present		1C
TS22: trachea epithelium	Absent		1C

Structure	Level	Pattern	Image	Note
TS23: lung	Present	Regionally restricted	1D	Specific staining was present in nuclei of subepithelial fibroblasts and adjacent columnar epithelial cells of branching airways. Mesenchymal cells distal from developing airways were devoid of specific staining.
TS23: lung epithelium	Present		1D
TS23: bronchiole	Present	Regionally restricted	1D	Staining was particularly prominent at airway branch points of terminal airways with columnar epithelia.
TS23: trachea epithelium	Absent		1D

Structure	Level	Pattern	Image	Note
TS24: terminal bronchiole	Present		2B	Specific staining was seen in nuclei of columnar and cuboidal epithelial cells of terminal conducting airways and in adjacent subepithelial fibroblasts.
TS24: terminal bronchiole epithelium	Present		2B
TS24: bronchiole	Present	Regionally restricted	2B	Positive staining was detected in nuclei of low cuboidal epithelia at branch points just before the entrance to developing alveolar ducts.
TS24: alveolar system	Absent		2B	Staining was absent from flattened epithelial cells of alveolar ducts and early alveolar sacs.
TS24: trachea epithelium	Absent		2B

Structure	Level	Pattern	Image	Note
TS25: lobar bronchus	Present		2C	Nuclei of large conducting airway epithelia cells and some adjacent subepithelial fibroblasts continue to show positive immunostaining.
TS25: terminal bronchiole epithelium	Present		2C	Staining was detected in cuboidal epithelial cells of terminal bronchioles.
TS25: alveolus epithelium	Absent		2C	Epithelial cells of the thin-walled developing alveolar sacs showed no staining.
TS25: trachea epithelium	Absent		2C

Structure	Level	Pattern	Image	Note
TS27: terminal bronchiole epithelium	Present	Non-Uniform	2D	Staining was seen in some but not all epithelial cells of terminal conducting airways.
TS27: lobar bronchus	Present		2D	Specific staining was present in some subepithelial fibroblasts and isolated epithelial cells of large conducting airways and terminal bronchioles.
TS27: terminal bronchiole	Present		2D	Specific staining was present in some subepithelial fibroblasts and isolated epithelial cells of large conducting airways and terminal bronchioles.
TS27: alveolus epithelium	Absent		2D	Epithelial cells of early alveolar sacs continued to be devoid of specific staining.

Structure	Level	Pattern	Image	Note
TS28: lobar bronchus epithelium	Present	Single cells		Staining was seen rarely in isolated conducting airway epithelial cells.