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Histological Variations in Myoepithelial Cells and Arrectores Pilorum Muscles among Caudal, Metatarsal and Preorbital in Hokkaido Sika Deer (Cervus nippon yesoensis Heude, 1884)

Nobuo OZAKI1), Masatsugu SUZUKI1)* and Noriyuki OHTAISHI1)

1)Laboratory of Wildlife Biology, The Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku, Sapporo 060–0818, Japan

(Received 1 April 2003/Accepted 15 October 2003)

ABSTRACT. The morphological characteristics of myoepithelial cells and arrectores pilorum muscles were investigated in caudal, metatarsal and preorbital glands of Hokkaido sika deer (Cervus nippon yesoensis Heude, 1884) using immunohistochemistry for α-smooth muscle . In the metatarsal, preorbital and general skin glands, layers continuously embraced the secretory , while in the caudal , discontinuous myoepithelial cell rows surrounded the tubules. There was a trend that the widths of the myoepithelial cells of the caudal and preorbital glands appeared to be thinner than those of the metatarsal and general skin glands. In the metatarsal gland, the arrectores pilorum muscles were highly developed and considerably larger than those in other skin glands. KEY WORDS: arrectores pilorum muscle, myoepithelial cell, sika deer. J. Vet. Med. Sci. 66(3): 283–285, 2004

The specialized skin glands in the cervid species include were incubated for 15 min at room temperature with a bioti- forehead, preorbital, tarsal, metatarsal, interdigital and cau- nylated rabbit antibody against mouse IgG, IgA and IgM dal glands [15], most of which contain both apocrine and (Nichirei). Then they were rinsed three times (10 min each) sebaceous glandular elements [1, 7, 12]. In Hokkaido sika in PBS and incubated for 10 min at room temperature in a deer (Cervus nippon yesoensis Heude, 1884), the existence streptavidin-biotin peroxidase complex (Nichirei). After of caudal, metatarsal and preorbital glands were confirmed three rinses in PBS, the peroxidase activity was visualized [4]. Some of their histological characteristics have already by incubating in diaminobenzidine solution (Histofine Sim- been reported [4], however, the physiological mechanisms ple Stain DAB solution, Nichirei). Finally the sections were of secretions remain unknown. Since specialized skin lightly counterstained with Mayer’s hematoxylin solution glands are considered to work as scent glands [9], their (Wako Pure Chemical, Osaka, Japan). The immunohis- secretory processes and product properties are largely tochemical specificity was tested by replacing the specific related to ecology and behavior of the species. So in the antibodies with non-immune serum. present study, we investigated the morphological character- In the apocrine glandular region of all skin glands, immu- istics of myoepithelial cells and arrectores pilorum muscles noreactivity specific for α-smooth muscle actin was found in caudal, metatarsal and preorbital glands of Hokkaido sika in myoepithelial cells and smooth muscle layer of the blood deer using immunohistochemistry for α-smooth muscle vessels (Fig. 1). Unlike the infraorbital gland of Japanese actin. serow (Capricornis crispus) [2], variation in the immunore- Tissues of those specialized skin glands and general skin activity of myoepithelial cells within each skin gland was glands of the buttocks were collected from four female deer not obvious. In the metatarsal and preorbital glands and (one year and older) that were humanely and legally shot in general skin glands, immunoreactive myoepithelial cell lay- Shari District in Hokkaido, Japan, in August 2000. Ages of ers continuously embraced the secretory epithelium (Figs. animals were estimated on deciduous tooth changes [6]. 1a, b, c), while in the caudal gland, discontinuous immu- The tissues were fixed in 10% formalin neutral buffer solu- noreactive cell rows surrounded the apocrine tubules (Fig. tion (pH 7.4) and embedded in paraffin for light-micro- 1d). There was a trend that the widths of the myoepithelial scopic immunohistochemistry. cells of the caudal and preorbital glands appeared to be thin- The 5 µm thick sections were dewaxed and incubated for ner than those of the metatarsal and general skin glands 45 min in 3% H2O2-methanol and then in 10% normal rabbit (Figs. 1b, d). serum (Histfine Kit, Nichirei Co., Tokyo, Japan) for 20 min In the sebaceous glandular region of all the skin glands, at room temperature. The sections were then incubated for obvious immunoreactivity was detected in the smooth mus- 20 min at room temperature with a mouse monoclonal anti- cle of blood vessels, arrectores pilorum muscles and around body against human α-smooth muscle actin (N1584, Dako hair follicles. It was noticeable that the arrectores pilorum Co., California, U.S.A.). After three washes (10 min each) muscles in the metatarsal gland were highly developed and in 0.01 M phosphate-buffered saline (PBS, pH 7.2), they considerably larger than those in the general skin glands, and enclosed the sebaceous glands which were also highly *CORRESPONDENCE TO: SUZUKI, M., Laboratory of Wildlife Biology, The Graduate School of Veterinary Medicine, Hokkaido Univer- developed (Fig. 2). There were no great differences in the sity, Kita-ku, Sapporo 060–0818, Japan. appearance of the arrectores pilorum muscles between the 284 N. OZAKI, M. SUZUKI AND N. OHTAISHI

Fig. 1. Immunostaining for α-smooth muscle actin of the metatarsal gland (a), preorbital gland (b), general skin gland (c) and caudal gland (d). In the metatarsal and preorbital glands and general skin glands, immunoreactive myoepithelial cell layers con- tinuously embrace the secretory epithelium, while in the caudal gland, discontinuous immunoreactive cell rows surround the apocrine tubules. There is a trend that the widths of the myoepithelial cells of the caudal and preorbital glands appear to be th in - ner than those of the metatarsal and general skin glands. L: glandular lumina. *: immunoreactive smooth muscle of blood ves- sels. Bars = 40 µm.

Fig. 2. Immunoreactivity specific for α-smooth muscle actin is seen in arrectores pilorum muscles (arrows). It is noticeable that the arrectores pilorum muscles in the metatarsal gland were highly developed and considerably larger than those in the general skin glands, and enclose the sebaceous glands (SG) which are also highly developed. HF: hair follicles. AG: apocrine glands. *: immunoreactive smooth muscle of blood vessels. Bar = 400 µm. VARIATIONS AMONG SKIN GLANDS IN SIKA DEER 285 caudal gland and in the general skin glands except that the Both sebaceous and sticky apocrine products from the distribution of those in the caudal gland were restricted to a metatarsal region easily adhere to leaves and sprigs of shallow portion of the corium and were not seen in the apo- ground cover. In addition, those smells may last longer than crine glandular region. The arrectores pilorum muscles in that of volatile secretions. This would be of advantage to the preorbital gland appeared to be fewer and smaller than indicate the trail of an animal to others, and adaptive in those in the general skin glands. maintaining the social group in forest and woodland habi- The present study demonstrated the variations in the tats. degree of development of the myoepithelial cells among the We thank the staff of the Shiretoko National Park Nature specialized skin glands of Hokkaido sika deer. It has been Center and members of the Hokkaido Hunting Association suggested that the myoepithelial cells of exocrine glands in Shari Town for their assistance with the collection of develop better to provide compression pressure for glandu- samples. We are grateful to Dr. T. Iwanaga of Hokkaido lar product expulsion, as the viscosity of the glandular prod- University for helpful suggestions and support throughout uct is higher [11, 13]. Therefore, the morphological the laboratory analyses. variations of myoepithelial cells among these glands may reflect the variations in their secretion properties. It is REFERENCES implied that the viscosity of the apocrine products from the metatarsal gland is higher than those from caudal and preor- 1. Apollonio, M. and Vailati, G. 1996. Z. Säugetierkunde 61: bital glands. It was reported that a sticky secretion, which 321–326. adhered to the cutis surface of the metatarsal gland of Hok- 2. Atoji, Y., Yamamoto, Y. and Suzuki, Y. 1995. European J. kaido sika deer, was observed [5]. However, we directly Morphol. 33: 237–246. 3. Geist, V. 1998. Deer of the World. Stackpole Books, Mechan- observed that the cutis surface of the caudal gland appeared icsburg. to be dry and smooth. In reindeer (Rangifer tarandus L), 4. Kamewaka, Y. 1993. Skin glands in Hokkaido sika deer. Mam- chemical analysis using gas chromatography also revealed malian Sci. 33: 18–20 (in Japanese). that the secretion from the caudal gland consisted of vola- 5. Kamewaka, Y. 1994. Graduation thesis of Faculty Vet. Med., tiles [10]. These observations are in agreement with our Hokkaido Univ., Japan (in Japanese with English summary). hypothesis about the relationship between myoepithelial 6. Koike, H. and Ohtaishi, N. 1985. J. Archaeol. Sci. 12: 443– cell development and secretion property in specialized skin 456. glands of sika deer. To verify that, detailed chemical and 7. Lewin, V. and Stelfox, J. G. 1967. Can. Field Nat. 81: 63–66. histological analyses of the products from these glands are 8. Morohashi, M. 1984. pp. 326–339. In: Jintaisoshikigaku 2 (Kiyodera, M. and Ogawa, K. eds.), Asakura-shoten, Tokyo (in indispensable. Japanese). Our study revealed that the arrectores pilorum muscles in 9. Muller-shuwarze, D. 1993. pp. 223–234. In: Biology and Man- the metatarsal gland were extraordinarily developed. Previ- agement of The Cervidae (Wemmer, C. M. ed.), Smithsonian ous research has indicated that the motion of the skin Institution Press, Washington, D. C. induced by contraction of this muscle promotes discharge of 10. Muller-shuwarze, D., Quay, W. B. and Brundin, A. 1977. J. cell products from the [8]. This means that Chem. Ecol. 3: 591–601. the erection of white hair, that covers metatarsal gland 11. Nagato, T., Yoshida, H., Yoshida, A. and Uehara, Y. 1980. region, and discharge of sebaceous products, happen syn- Cell Tissue Res. 209: 1–10. chronously. It was reported that the hair on or around spe- 12. Quay, W. B. and Muller-shuwarze, D. 1970. J. Mamm. 51: cialized skin glands stands erect when animals are alerted 675–694. and act as a visual warning [3]. This visual alarm effect, 13. Redman, R. S. 1994. Microsc. Res. Tech. 27: 25–45. 14. Suzuki, M., Kamewaka, Y., Yamanaka, M., Iwanaga, T. and therefore, is considered to be reinforced by the olfactory Ohtaishi, N. 2001. Can. J. Zool. 79: 416–419. effect of metatarsal secretion that discharged simulta- 15. Whitehead, G. K. 1993. Encyclopedia of Deer. Swan Hill neously. Press, Shrewsbury.