Advillin Is Expressed in All Adult Neural Crest-Derived Neurons

Advillin expression by Merkel cells (M). A, Glabrous skin. B, Hairy skin. Leftmost panels show advillin promoter-driven EGFP fluorescence. Other panels show advillin immunoreactivity in wild-type mice. The bottom right panel additionally shows hair follicles cut parallel to the skin surface, surrounded by advillin-positive axons.

Advillin is enriched in nonpeptidergic nociceptors. A, Advillin immunoreactivity is strong in the spinal nerve but weak in the dorsal root. In the cord, intense advillin immunoreactivity is only apparent in inner lamina II. Inset, Advillin promoter-driven EGFP is distributed to all primary afferent axons. B, Advillin immunoreactivity is enriched in IB4-binding neurons (arrows). Double arrows indicate rare IB4-binding neurons with weak advillin immunoreactivity, and the asterisk indicates an even more rare IB4-negative neuron with positive advillin immuoreactivity. C, Scatterplots showing IB4 binding and advillin intensity (intensity of IB4 binding indicated by brightness of green, IB4-negative profiles indicated by unfilled circles) as a function of profile area. There is a strong, significant correlation between IB4-binding and advillin immunoreactivity.

Advillin is expressed throughout the mouse autonomic neuronal lineage. In A–E, the leftmost column is EGFP fluorescence from the advillin-EGFP mouse. A, SCG (sympathetic). B, The otic ganglion (cranial parasympathetic). C, major pelvic ganglion (mixed sympathetic parasympathetic). D, Enteric neurons (Meissner’s plexus). E, Advillin is not expressed in the adrenal medulla. F, tdtomato fluorescence in the DRG and stellate and lumbar sympathetic chain ganglia following tamoxifen-induced nuclear translocation of advillin promoter-driven CreERT2 expression in a ^flstop^fl-tdtomato reporter mouse. Red asterisks indicate rare non-recombined neurons.

Advillin in spine-like structures on the pelvic ganglion neuron axonal initial segment. A, Confocal stack and 3D reconstruction of an advillin-intense neuronal pair with spine-like structures projecting from the axonal initial segment (arrows). B, Examples of advillin-bright pairs with axonal spines. ChAT-positive preganglionic axons contact neurons at these spines. The lower right panel of B shows an occasional binucleate neuron, also advillin-intense and with axonal spines.

Advillin expression in rat sensory and autonomic neurons. A, DRG. Note intense advillin immunoreactivity at the distal pole of the DRG (arrow), but not in the dorsal root. RC, rami communicantes containing sympathetic axons. B, Stellate ganglion (sympathetic). C, Otic ganglion (cranial parasympathetic). D, Major pelvic ganglion (mixed sympathetic/parasympathetic).

Advillin expression in non-human primate sensory and autonomic neurons. A, DRG. VR, ventral root (advillin-negative). B, Thoracic sympathetic chain ganglion.

Axonal advillin expression in sympathetic target tissues. A, Mouse skin. Note colocalization between TH and advillin around a blood vessel (bv). A fasciculated nerve bundle (nb) is also apparent. B, C, Whole-mount rat iris. B, Corneal surface of the iris showing heavily-innervated bv and ChAT-positive nbs. C, Lens surface of the iris showing sympathetic and parasympathetic innervation of the dilator and constrictor muscles, respectively.