Figure 1. Immunohistochemical analysis of PKC ßI (a,b,c) and ßII (d,e,f) expression in the rat tooth germ at the cap (a,d), early bell (b,e), and late bell (c,f) stages (scale bars, 100 µm). At the cap stage, no immunoreactivity for PKC ßI was seen (a). At the early bell stage, the inner enamel epithelium in the cervical loop shows strong immunoreactivity for PKC ßI (b'). At the late bell stage, the inner enamel epithelium in the cervical loop in the dental papilla shows weak immunoreactivity for PKC ßI (c'). At the cap stage, no immunoreactivity for PKC ßII can be seen (d). At the early bell stage, the inner enamel epithelium in the cervical loop shows strong immunoreactivity for PKC ßII (e'). At the late bell stage, the inner enamel epithelium in the cervical loop shows weak immunoreactivity for PKC ßII (f').