Probe:	Itm2a cDNA3
Probe preparation:	Antisense labelled with digoxigenin RNA

Structure	Level	Pattern	Image	Note
TS17: oral region	Present	Regionally restricted	1A	Expressed in the ectomesenchyme of the mandible, whereas no specific signal was found in the epithelial and mesenchymal cells corresponding to the predicted lower first molar region.

Structure	Level	Pattern	Image	Note
TS20: mandibular process	Present	Regionally restricted	1B	Expressed in the ectomesenchyme of the mandible, whereas no specific signal was found in the epithelial and mesenchymal cells corresponding to the predicted lower first molar region.

Structure	Level	Pattern	Image	Note
TS21: tooth epithelium	Absent		1C
TS21: tooth mesenchyme	Absent		1C

Structure	Level	Pattern	Image	Note
TS22: tooth epithelium	Absent		1D
TS22: tooth mesenchyme	Absent		1D

Structure	Level	Pattern	Image	Note
TS23: primary enamel knot	Strong	Regionally restricted	1E	Expressed in central epithelial cells.
TS23: inner enamel epithelium	Present		1E
TS23: outer enamel epithelium	Present		1E
TS23: dental lamina	Weak		1E
TS23: dental papilla	Weak		1E	Very weak expression.
TS23: dental sac	Weak		1E	Very weak expression.
TS23: blood vessel	Present	Regionally restricted	1E	Expressed in the blood vessels in the dental pulp.

Structure	Level	Pattern	Image	Note
TS24: enamel knot	Strong	Regionally restricted	1F	Expressed in the outer enamel epithelium, inner enamel epithelium and central epithelial cells.
TS24: inner enamel epithelium	Present	Regionally restricted	1F
TS24: outer enamel epithelium	Present	Regionally restricted	1F
TS24: dental lamina	Weak		1F
TS24: dental papilla	Weak		1F	Very weak expression.
TS24: dental sac	Present		1F

Structure	Level	Pattern	Image	Note
TS25: inner enamel epithelium	Strong		1G	Increased expression in the inner enamel epithelium. Expression in the inner enamel epithelium was stronger than that observed in the outer enamel epithelium.
TS25: outer enamel epithelium	Present		1G
TS25: enamel organ	Present	Regionally restricted	1G	Expressed in the central epithelial cells of the enamel organ near the cervical loop.
TS25: dental papilla	Weak		1G
TS25: dental sac	Weak		1G

Structure	Level	Pattern	Image	Note
TS26: enamel organ	Present		1H	Similar to that on E17.
TS26: dental papilla	Present	Regionally restricted	1H	Expressed in the site where the cusps had formed.
TS26: dental sac	Weak		1H

Structure	Level	Pattern	Image	Note
TS27: inner enamel epithelium	Present	Regionally restricted	2A , 2B	Expressed throughout the preodontoblasts localized at the presumptive cusp sites of the dental pulp and the inner enamel epithelium.
TS27: outer enamel epithelium	Weak		2A , 2B
TS27: stratum intermedium	Weak		2A , 2B
TS27: dental pulp	Present	Regionally restricted	2B , 2A	Expressed in the preodontoblasts localized at the presumptive cusp sites.
TS27: blood	Present	Regionally restricted	2B , 2A	Expressed in the blood vessels in the dental pulp.

Structure	Level	Pattern	Image	Note
TS27: enamel organ	Strong	Scattered	2D , 2G , 2E	Strong expression in ameloblasts and odontoblasts. Expressed in the preameloblasts. Weak expression in the preodontoblasts.
TS27: stratum intermedium	Present		2G , 2D , 2E
TS27: dental sac	Present		2D	Increased expression.

Structure	Level	Pattern	Image	Note
TS27: enamel organ	Strong	Regionally restricted	3A	Strong expression in the ameloblasts and odontoblasts. Expressed in the preameloblasts and preodontoblasts.

Structure	Level	Pattern	Image	Note
TS27: enamel organ	Strong	Regionally restricted	3B	Strong expression in the ameloblasts and odontoblasts. Expressed in the preameloblasts and preodontoblasts.

Structure	Level	Pattern	Image	Note
TS28: enamel organ	Strong	Regionally restricted	3C	Strong expression in the osteoblasts which rimmed the alveolar bone surrounding the tooth crown. Expressed in the preodontoblasts.

Structure	Level	Pattern	Image	Note
TS28: enamel organ	Strong	Regionally restricted	3D , 3E	Strong expression in ameloblasts and odontoblasts. Reduced expression in the odontoblasts and ameloblasts in the presumptive cusp sites.
TS28: Hertwig's epithelial root sheath	Strong		3E , 3D	Strong expression in the Hertwig's epithelial root sheath around the root apex.
TS28: outer enamel epithelium	Trace		3E , 3D	Very weak expression in the outer enamel epithelium and the stratum intermedium.
TS28: stratum intermedium	Trace		3E , 3D	Very weak expression in the outer enamel epithelium and the stratum intermedium.

Structure	Level	Pattern	Image	Note
TS28: enamel organ	Strong	Regionally restricted	4B , 4C	Strong expression in ameloblasts and odontoblasts. Reduced expression in the odontoblasts and ameloblasts in the presumptive cusp sites.
TS28: Hertwig's epithelial root sheath	Strong		4C , 4B	Strong expression in the Hertwig's epithelial root sheath around the root apex.
TS28: outer enamel epithelium	Trace		4C , 4B	Very weak expression in the outer enamel epithelium and the stratum intermedium.
TS28: stratum intermedium	Trace		4C , 4B	Very weak expression in the outer enamel epithelium and the stratum intermedium.

Structure	Level	Pattern	Image	Note
TS28: enamel organ	Strong	Regionally restricted	4F , 4E	Strong expression in the odontoblasts. Weak expression in the developing periodontal membrane.
TS28: Hertwig's epithelial root sheath	Strong		4F , 4E	Strong expression in the Hertwig's epithelial root sheath around the root apex.

Structure	Level	Pattern	Image	Note
TS20: tongue	Present	Regionally restricted		Expressed in the central area of the mandible, which corresponded to a part of the tongue primordium.