Dissection procedures for harvesting whisker hair follicles from rat whisker pads. A) A circle outlines the location of the whisker pad in a rat. B) Diagram illustrates the organization of whisker hairs in a rat whisker pad. Each whisker hair is represented by a round dot and designated according to its location in a whisker pad, e.g. A1 is the first whisker in the first row. C) A whisker pad was cut off from the face of a rat and placed in a dish with its hairy side up. D-E) Images show the tissue side (inside) of the whisker pad before (D) and after (E) the removal of fat tissues. Individual whisker hair follicles can be clearly seen after the removal of fat tissues, and one of them is indicated by an arrow. F-G) Pulling out whisker hair follicles. H) Image shows a whole whisker hair follicle with its whisker hair (arrow indicated) and whisker nerve (arrowhead indicated) after being pulled out of the whisker pad. I) Schematic diagram shows some main structures of a rat whisker hair follicle. CA, capsule; WN, whisker nerve; CS, cavernous sinus; GM, glassy membranes; RS, ring sinus; MC, Merkel cells; ORS, outer root sheath; WH, whisker hair shaft.