Click on image to view larger version.

Fig. 1. Histological and ultrastructural analysis of the Smo mutant tooth
phenotype at 1 dpp. Parasagittal sections through control (A) and mutant (B)
molars showing fusion between the first (m1) and second (m2) molars in the
mutant. Frontal sections through molars from control (C) and mutant (D) pups.
Note the absence of the dental cord (dc) and the cellular paucity and lack of
vascularization in the mutant stellate reticulum (sr). The mis-positioned red
blood cells in the SR in C is an artefact and therefore does not indicate the
exact location of blood vessels. High magnifications of boxed areas in C and D
are included as insets. Parasagittal sections at the anterior segment of
incisors from control (E) and mutant (F) pups. Note the severe alterations in
the ameloblast (a) and stratum intermedium (si) layers in the mutant. TEM
micrographs from control (G) and mutant (H) incisors. The white double-headed
arrows indicate ameloblast length in G and H. dp, dental papilla mesenchyme;
G, Golgi; o, odontoblasts; Tp, Tomes' process; tw, terminal web. Scale bars:
500 µm (A,B); 200 µm (C,D); 50 µm (E,F); 5 µm (G,H).