Figure 3. Genetic disruption of peripheral target innervation does not affect region-specific central arbor morphologies.

A, C, Whole mount CFP immunostaining of sparse labeled 2–3pw Mrgprd^CreERT2; Ret^{f(CFP) / +} (control, A) and Mrgprd^CreERT2; Ret^{f(CFP) / null} (mutant, C) DRGs (0.5 mg tamoxifen at E16.5-E17.5). B, D, CFP immunostaining of sectioned glabrous skin shows epidermal endings in control (B) but not mutant (D) mice, indicating a lack of peripheral terminals in Ret null nociceptors. White arrows, mature epidermal endings. White arrowheads, dermal axonal bundles. E-H, CFP immunostaining of serial DH sections from control (E&F) and mutant (G&H) mice shows sparse labeled terminals. I, Quantification of the number of CFP+ neurons / DRG. n = 14–22 DRGs from 3 animals per genotype. J, Maximal mediolateral width of sparse labeled neurons from control and mutant mice shows that the round-vs.-long distinction is still present in mutant mice. n = 239 (mutant), 287 (control) neurons from 3 mice per genotype. Scale bars = 100 µm (A&C), 20 µm (B&D), 50 µm (E-H).