118 Morioka et al. Localization of actin by immunoperoxidase method The localization of actin in the skin, hair follicles, and dermal tissues was found to be essentially the same as that of nonmuscle myosin II (Fig. 4). Namely, the following areas were stained: spinous and granular layers of the epidermis (Fig. 4A and C), some undetermined cells of the hair matrix (Fig. 4D and E, thick arrows), outer root sheath of the hair follicle (Fig. 4B thin, long arrow ORS; 4C, thin, long arrows ORS; and 4D, thin arrows), interfollicular dermal cells, and dermal muscle (for example, Fig. 4C and F). As shown in Figure 4F, the distribution of actin is not uniform in capsule cells. The outermost cells exhibited dense staining, though Fig. 4. Localization of actin in skin and hair follicles. Results of control experiments were the same with those shown in Figure 4. The magnifi- cation of A, B, D, E and F are the same. Bars100 m. A) In the epidermis, a, b, c, and d represent the basal, spinous, granular, and innermost keratinized layer, respectively. B) Middle (left side) and inner (right side) areas of dermis in dorsal skin. ORS, outer root sheath. Small arrows and arrowheads denote the hair shafts including positively-stained medulla. C) Facial skin and vibrissal follicle. The basal layer of mystacial skin (a), and its extension surrounding the vibrissa (a*) are shown. RS, ring sinus; DM, dermal muscle; ORS, outer root sheath; Cs, capsule; Sn, Sinus; HS, hair shaft. D, E) The positive cells of hair matrix (thick arrows) and middle height outer root sheath (thin arrows) are seen. The border between hair matrix and dermal papilla (*) is indicated by dotted line. F) An oblique section of mystacial vibrissal follicle sectioned at the intermediate height. Cs, capsule; Sn, sinus; ORS, outer root sheath; IRS, inner root sheath; HS, hair shaft; DVN, deep vibrissal nerve; DM, dermal muscle.