FAM20A immunohistochemistry. Top: FAM20A localization during mouse first maxillary molar development. (A1-A3) At post-natal day 5 (PN5), FAM20A signal was observed in secretory-stage ameloblasts, odontoblasts, and in oral epithelium (A3). (B1-B4) At post-natal day 8 (PN8), FAM20A signal was minimal in transition or early maturation-stage ameloblasts, but strong in odontoblasts and the oral epithelium (B2 and B4). (C1-C2) At post-natal day 11 (PN11), no FAM20A signal was observed in maturation-stage ameloblasts. FAM20A was detected in odontoblasts and in oral epithelium. A band of cells positive for FAM20A was observed in the connective tissue between the oral epithelium and the developing cusp tip. The box in C1 corresponds to the position of panel C2. (C3) On post-natal day 14 (PN14), just prior to eruption, FAM20A signal was evident in the dental follicle above the molar cusp tips. (D1-D3) FAM20A localization in four-week-old mouse kidney. Key: bc, Bowman’s capsule; c, renal cortex; m, renal medulla; oe, oral epithelium. Blue is DAPI-stained nuclei, green is FAM20A signal, solid arrowheads indicate ameloblasts, and hollow arrowheads indicate odontoblasts.