Antibody:

anti-Hes7

Structure	Level	Pattern	Image	Note
TS17: tail unsegmented mesenchyme	Present	Regionally restricted	1C , 1A	Expressed in the middle region and subsets of cells in the posterior end during phase I.

Structure	Level	Pattern	Image	Note
TS17: tail unsegmented mesenchyme	Present	Regionally restricted	1G , 1I	Expressed in the anterior region during phase II.

Structure	Level	Pattern	Image	Note
TS17: tail unsegmented mesenchyme	Present	Regionally restricted	1O , 1M	Expression further moved to prospective somite S-1, and new expression was initiated in the posterior during phase III.

Structure	Level	Pattern	Image	Note
TS17: tail unsegmented mesenchyme	Absent		1U , 1S

Structure	Level	Pattern	Image	Note
TS17: tail unsegmented mesenchyme	Present	Regionally restricted	2A , 2C , 2B	Expressions of Notch1 and Hes7 were clearly separated in the middle to anterior. In the posterior end, expressions of Notch1 and Hes7 were intermingled, and subsets of cells even coexpressed Notch1 and Hes7.

Structure	Level	Pattern	Image	Note
TS17: tail unsegmented mesenchyme	Present	Regionally restricted	2E , 2D , 2F	Expressions of Notch1 and Hes7 were clearly separated in the middle to anterior. In the posterior end, expressions of Notch1 and Hes7 were intermingled, and subsets of cells even coexpressed Notch1 and Hes7.

Structure	Level	Pattern	Image	Note
TS17: tail unsegmented mesenchyme	Present	Regionally restricted	2G , 2H , 2I	Expressions of Notch1 and Hes7 were clearly separated in the middle to anterior. In the posterior end, expressions of Notch1 and Hes7 were intermingled, and subsets of cells even coexpressed Notch1 and Hes7.

Structure	Level	Pattern	Image	Note
TS17: tail unsegmented mesenchyme	Present	Scattered	2K , 2J , 2L	In the posterior end, expressions of Notch1 and Hes7 were intermingled. Expression domains were not clearly segregated in either the S0 or S-1 region. Some cells even coexpressed Hes7 and Notch1.