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. Author manuscript; available in PMC: 2016 Jun 1.
Published in final edited form as: Dev Dyn. 2015 Apr 24;244(6):713–723. doi: 10.1002/dvdy.24264

Figure 1. Cell compaction-dependent odontogenic induction is reversible.

Figure 1

(A) Hematoxylin and eosin stained (H&E) histological sections showing development of the lower molar tooth in the mouse embryo. (B) Graph showing mesenchymal cell densities measured in non-condensed area (NCA) or condensed area (CA). (C) Fluorescence immunomicrograph showing Pax9 protein in the tooth germ at E14. (D) Phase contrast micrographs showing mesenchymal cells cultured for 16 hr on microfabricated circular FN islands (500 μm diameter) in vitro at low or high plating density (0.2 or 2.5X105 cells/cm2, respectively). (E) Graph showing induction of odontogenic factors (Pax9 and Msx1) in mesenchymal cells cultured under the same conditions as in (D). (F) Graph showing induction of Pax9 in the cells plated and re-plated at various combinations of low (L) and high (H) density. Note that Pax9 induction is cell compaction-dependent and reversible. Dashed lines indicate the epithelial-mesenchymal interface, and tip of white arrows abut on the lower edge of the condensed mesenchyme. Scale bars represent 50 μm for A and C, 100 μm for D; *p < 0.01.