Antibody:	Anti-EGF
Detection system:	Biotinylated secondary antibody/[Strept]avidin coupled to horseradish peroxidase

Structure	Level	Pattern	Image	Note
TS18: embryo	Present	Regionally restricted	3a	Expression was detected in a sheet of epitopes separating the medial aspect of the primitive lungs from the mediastinal mesenchyme. Expression was detected within individual mesenchymal cells and in the adjacent extracellular matrix.
TS18: embryo mesenchyme	Present		3a
TS18: respiratory system	Present	Regionally restricted	3a	Expression was detected within individual airway lining cells, as shown in the inset.

Structure	Level	Pattern	Image	Note
TS23: lung	Present	Regionally restricted	3b	Expression was detected both within cells lining the primitive airway and in the cells and extracellular matrix immediately surrounding the airway of the lungs.

Structure	Level	Pattern	Image	Note
TS25: lung	Present	Regionally restricted		Expression was similar to E15.0, except that immunoreactivity was not as evident at the level of primitive terminal air sacs.