Antibody:	Anti-Sox9
Detection system:	Secondary antibody coupled to Cy3
Assay notes:	Two Sox9 antibodies were described: MGI:6455064 and MGI:6455215); either could have been used in this assay.

Structure	Level	Pattern	Image	Note
TS17: pancreas primordium	Present	Regionally restricted	1A	Expression was detected in dorsal and ventral pancreas. There was no co-expression with Gcg-expressing differentiated cells.

Structure	Level	Pattern	Image	Note
TS17: pancreas primordium	Present	Regionally restricted	1B	Expression was detected in dorsal and ventral pancreas. Pdx1-positive primary pancreatic progenitor cells co-expressed Sox9.
TS17: duodenum	Absent		1B

Structure	Level	Pattern	Image	Note
TS20: pancreas	Present	Regionally restricted	1C	Expression was detected in dorsal and ventral pancreas. There was no co-expression with Gcg-expressing differentiated cells.

Structure	Level	Pattern	Image	Note
TS20: pancreas	Present	Regionally restricted	1D	Expression was detected in dorsal and ventral pancreas. Pdx1-positive primary pancreatic progenitor cells co-expressed Sox9.

Structure	Level	Pattern	Image	Note
TS22: pancreatic duct	Present		1E	Expression was detected in secondary pancreatic progenitor cells along the ducts. Co-expression was noted with Pdx1.
TS22: pancreas	Present	Regionally restricted	1E	Sox9 was detected in the progenitor cells in the ducts but not in the Pdx1-stained differentiated cells.

Structure	Level	Pattern	Image	Note
TS28: pancreatic duct	Present		1F	Expression persisted in the cells along the major ducts.
TS28: pancreatic acinus	Absent		1F	Expression was not detected in the small distal intraacinar ducts.

Structure	Level	Pattern	Image	Note
TS23: pancreatic duct	Present		1H , 1G , 1H inset red	A subset of Sox9-positive cells in the ducts co-expressed Neurog3.

Structure	Level	Pattern	Image	Note
TS22: pancreatic duct	Present		2A , 2C	A subset of pancreatic duct cells co-expressed Sox9 and Neurog3.

Structure	Level	Pattern	Image	Note
TS28: islets of Langerhans	Present	Patchy		Patchy immunoreactivity was detected in the cytoplasm of beta-cells in the islets of Langerhans.