Figure 3.

Er81 is absolutely required in neurons, but not Schwann cells, for Pacinian corpuscle development. A, Nestin^Cre crossed to a ROSA-tdTomato (red) reporter allele exhibits recombination in innervating fibers but not in the S100⁺ (green) Schwann cells of the Pacinian corpuscle end organ. B, C, Anti-ER81 immunostaining of DRG sections from P7 Nestin^Cre;Er81^f/+ control (B) and Nestin^Cre;Er81^f/− conditional mutant (C) shows ablation of ER81 expression in neurons in the mutant mice. D–F, Anti-S100 staining of hindlimb sections from P7 control (D) and conditional mutant (E) mice shows a lack of S100⁺ Pacinian corpuscles surrounding the fibula in neural-specific mutant mice (27.83 ± 1.167 PC per leg in Nestin^Cre;Er81^f/+ control, 0 ± 0 PC per leg in Nestin^Cre;Er81^f/− conditional mutant; p < 0.0001). G, Dhh^Cre crossed to a ROSA-tdTomato (red) reporter allele reveals reporter activity in S100⁺ (green) inner core Schwann cells of the Pacinian corpuscles, but not in the NFH⁺ (blue) innervating fiber. H, I, Pacinian corpuscles are present around the fibula in Dhh^Cre;Er81^f/+control (H) and Dhh^Cre;Er81^f/− conditional mutant (I) mice at P7. J, Quantification of serial leg sections reveals a significant decrease in the number of Pacinian corpuscles per leg in Schwann cell-specific Er81 mutants compared with controls (33.33 ± 3.756 PC per leg in Dhh^Cre;Er81^f/+controls, 15.00 ± 0.58 PC per leg in Dhh^Cre;Er81^f/− conditional mutants; p = 0.009). K, The average size of Pacinian corpuscles, measured by cross-sectional area, is significantly reduced in Schwann cell-specific Er81 mutants (410.1 ± 65.3 μm² in Dhh^Cre;Er81^f/+controls, 187.9 ± 30.9 μm² in Dhh^Cre;Er81^f/− conditional mutants; p = 0.037). N = 3 animals, 6 legs per genotype. Scale bars: A, D–I, 20 μm; B, C, 50 μm. *p < 0.05. **p < 0.01. ***p < 0.001. Error bars indicate SEM.