C- and Aβ-LTMR innervation of hair follicles in GFRα2-KO mouse back skin remains unchanged.

<p>(A–C) The images show two small caliber hair follicles with TH⁺ and TrkB⁺ LLEs. Immunoreactivity for the markers is localized in different populations of endings (C). The asterisks in (B) mark the two separate hair shafts. (D, E) The images demonstrate TH⁺ sensory innervation around small caliber hair follicles in wild-type (D) and KO (E) back skin. The arrowheads indicate obliquely cut hair follicles with TH⁺ LLEs. The small arrows mark hair follicles with few or no visible endings. Sebaceous glands (sg) around the follicles are indicated. No changes are obvious in the morphology of TH⁺ LLEs around GFRα2-KO hair follicles. (I, left side) The percentage of small hair follicles that are innervated by TH⁺ LLEs is similar between the genotypes (WT 87.8±6.4%, KO 90.6±1.1%; three animals/genotype, 60–80 small hair follicles/animal, U-test). (F, G) The morphology of NFH⁺ LLEs (arrowheads) appears similar between the genotypes. Double arrowheads point to nerve structures innervating the touch dome (located outside of the image). (I, right side) NFH⁺ LLEs remain in KO back skin (WT 88.7±0.8%, KO 81.6±3.6%; innervated follicles/total follicles, three animals/genotype, 60–80 small hair follicles/animal, U-test). Scale bars: 10 µm.