Figure 7.

Characterization of hyrax follicle-sinus complex (FSC) innervation at the ring sinus (RS) level (longitudinal planes of section). A) Characteristic innervation at the RS and cavernous sinus (CS) levels of a representative follicle-sinus complex from the caudal body. Arrowhead denotes a mesenchymal bulge at the ring sinus level in proximity to the ringwulst (RW). Large-caliber fibers from the deep vibrissal nerve (DVN) can be seen ascending superficially through the cavernous sinus, curving around the mesenchymal bulge to terminate as Merkel ending complexes (MECs). B) At the level of the ring sinus, club endings and MEC networks can be observed. A mesenchymal bulge at the ring sinus level in proximity to the ringwulst is visible (arrowheads), and presumptive “tangle” endings are apparent at the upper RS/lower ICB level as terminations of large-caliber fibers. C) Fine-caliber innervation is observed at the outer and inner conical body levels, whereas the ring sinus is characterized by dense, circumferential networks of MECs. The mesenchymal bulge proximal to the ringwulst is denoted by the arrowhead. D) Longitudinal lanceolate endings were present along the mesenchymal sheath at the upper extent of the ring sinus, but were relatively sparsely distributed. E) MECs terminate in the outer root sheath of the follicle at the ring sinus level, and large tangle endings were observed. Scale bars=300μm (A-D), 75μm (E). Cap = capsule, CS = cavernous sinus, DVN = deep vibrissal nerve, HP = hair papilla, ICB = inner conical body, LLEs = longitudinal lanceolate endings, MECs = Merkel ending complexes, OCB = outer conical body, RS = ring sinus, RW = ringwulst, TRB = trabeculae.