Fig. 4

In situ hybridization of T2Rs to the nostrils, lower lip, oral cavity, and top head skin showing the different abundances of T2R-expressing cells on these organs. Fish head illustrations at the lower left corners of panels (A), (C), (E), and (G) show the approximate position of the coronal sections depicted in the respective panels. (A) A quarter of a coronal head section including the nostril (enclosed in the rectangle). (B) Higher magnification image of the nostril in panel a, showing T2R-expressing cells in the nostril. (C) A coronal section of the lower lip, several T2R-expressing taste cells can be observed in several different taste buds in the lower lip. (D) Higher magnification of the area enclosed by the rectangle in panel (C). (E) A coronal section of the head including the oral cavity. (F) Higher magnification of the area enclosed by the rectangle in panel (E), showing the single T2R-labeled cell in this section of the oral cavity. (G) A quarter of a coronal head section showing the single T2R-labeled cell in the top head skin on this section. (H) Higher magnification of the area enclosed by the rectangle in panel (G). Scale bars are 50 µm (A–C, G), 20 µm (D, F, H), and 200 µm (E).