Localization and expression of Ddr2 in
dental and periodontal tissues. (A–H) X-gal
staining of Ddr2+/LacZ mice reveals Ddr2 expression in
the molars during development through adulthood. (A) At
P1, Ddr2 expression is observed in dental
papilla (dp) and the surrounding dental follicle (df) in
developing molars (high magnification in E). (B–D)
Ddr2-LacZ expression is selectively
high in dentin-producing odontoblasts (od) at P3, P7, and
P60. (F, G) High magnification also reveals
Ddr2 expression in odontoblasts
(od) and a subset of cells in dental pulp (dp). In a fully
erupted molar (D, H), Ddr2 is expressed
in PDL cells (pdl) and putative alveolar bone–associated
osteoblasts (ob). Black arrowheads point to the expression
sites. (I–L) Ddr2 expression
in odontoblasts (od) of lower incisors, in dental pulp
(dp), and around the labial cervical loop (lacl) at the
proximal end of the incisor (dashed lines). (J, L) Higher
magnification of boxed areas. No Ddr2
expression was seen in molar (F) or incisor (J)
ameloblasts (am). Scale bar: 100 µm in A–D, I, K; 20 µm in
E–H, J, L.