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. 2020 Jul 23;99(13):1478–1485. doi: 10.1177/0022034520941837

Figure 4.

Figure 4.

WGA and CTB tracing reveal similar comprehensive labeling and classification of molar neurons. (A) Collapsed image (maximum projection light sheet) of optically cleared right trigeminal ganglia with sensory neurons labeled from application of WGA–Alexa 488 (green) and CTB–Alexa 647 (magenta) to the maxillary first molar. Dorsal view with rostral orientation toward the left. Scale bar: 500 μm. L, lateral; R, rostral. (B) Panels highlight extensive overlap of CTB and WGA labeling. The magnified field is indicated by a white rectangle in panel A. Scale bar: 100 μm. (C) Images are shown for comparison from an optically cleared trigeminal ganglion with sensory neurons labeled by injection of spectrally distinct WGA and CTB tracers into the attached gingiva covering the hard palate. Note the larger number of small-diameter cells and the lower degree of overlap between the labels. Scale as shown in panel B. Similar results were obtained for these types of colabeling in 2 animals for each site of application. (D) Pie charts representing the transcriptomic classification of WGA- and CTB-labeled neurons innervating the palate (1635 neurons, 2 groups of 3 mice, 55 fields) and first and second maxillary molars (812 neurons, 4 groups of 3 mice, 97 fields) highlight that, whereas many classes of sensory neuron target the palate, the molar teeth are innervated primarily by C4 and C6 cells. (E) For cells targeting the molars (black solid bars) and the palate (gray open bars), fold enrichment of each class of neurons was calculated relative to prevalence in the whole ganglion (see Fig. 3B). Bar graph shows the mean + SEM (n = 4 groups, molars; 2 groups, palate) and the individual results from WGA (red dots) and CTB labeling (green dots). All classes other than C4 and C6 innervate the teeth less frequently than what would be expected (dashed line). See Appendix Table 2 for statistical analysis. (F) Distribution of diameters for CTB- and WGA-labeled cells targeting the molars (black solid bars) and the palate (gray open bars) as quantitated in tissue sections. CTB, cholera toxin B-subunit; WGA, wheat germ agglutinin.