Antibody:	Anti-K5
Detection system:	Secondary antibody coupled to Alexa Fluor

Structure	Level	Pattern	Image	Note
TS20: thymus primordium	Present		1B K5 E12.5 , 1B Merge E12.5	Expression was detected in the whole epithelium where it overlapped with Krt8 and Tbata.

Structure	Cell Type	Level	Pattern	Image	Note
TS23: thymus primordium	epithelial cell of thymus	Present		1B Merge E15.5 , 1B K5 E15.5	Smaller clusters of Krt8-Krt5+ cells were interspersed among Krt8+Krt5- subsets. Some Krt8+Krt5+ cells were maintained. Staining overlapped with Tbata.

Structure	Cell Type	Level	Pattern	Image	Note
TS28: thymus medulla epithelium	medullary thymic epithelial cell	Present		3A K5 , 3A Merge top	Krt5 is a marker for medullary thymic epithelial cells. Aire staining in mature medullary thymic epithelial cells co-localizes with Krt5 in those cells.

Structure	Cell Type	Level	Pattern	Image	Note
TS28: thymus medulla epithelium	medullary thymic epithelial cell	Present		3B Merge left , 3B K5 left	Krt5 is a marker for medullary thymic epithelial cells. Aire staining in mature medullary thymic epithelial cells co-localizes with Krt5 in those cells.

Structure	Cell Type	Level	Pattern	Image	Note
TS28: thymus medulla epithelium	medullary thymic epithelial cell	Present		3B K5 center , 3B Merge center	Krt5 is a marker for medullary thymic epithelial cells.

Structure	Cell Type	Level	Pattern	Image	Note
TS28: thymus medulla epithelium	medullary thymic epithelial cell	Present		3B K5 right , 3B Merge right	Krt5 is a marker for medullary thymic epithelial cells.