Brief Note Dorsal and Anal Glands in the Eastern Chipmunk, Tamias

Home , Chipmunk, Eastern chipmunk, Spermophilus, Tamias

BRIEF NOTE DORSAL AND ANAL GLANDS IN THE EASTERN CHIPMUNK, T AM I AS STRIATUS1

RICHARD H. YAHNER,2 B. L. ALLEN and WESLEY J. PETERSON, Department of Zoology and Microbiology, Ohio University, Athens, OH 45701

OHIO J. SCI. 79(1): 40, 1979

Scent marks are important mechanisms means of synchronizing mating activity of exchanging information among con- in both T. sibiricus (Dobroruka 1972) and specifics, orienting individuals within T. striatus (Yahner 1978). We, therefore, home ranges, or integrating reproductive inspected tissue in the dorsal and the and social behavior in many species of anal regions of T. striatus for the occur- mammals (Eisenberg and Kleiman 1972). rence of scent glands. For example, ground squirrels [Spermo- Two captive, adult male chipmunks philus spp.) frequently scent mark by were sacrificed, and the skins were re- rubbing large, macroscopic, dorsal glands moved and fixed in alcohol-formalin- against substrata (Steiner 1974). Size acetic acid. The skins were examined and use of dorsal glands in this genus are macroscopically, both at removal and related to social organization. The most after fixation, for the presence of dorsal social ground squirrels have large glands and anal glands. Portions of tissue from and frequently scent mark; in contrast, the skin of one male were removed from the least social species have smaller the central region of the shoulder blades glands and never scent mark, except per- and from the anal region. The tissue haps in a passive manner when indi- specimens were washed in running tap viduals accidently touch tunnels of en- water and then dehydrated by the trances to burrow systems during passage standard procedure in graded percentages (Kivett el al 1976). of ethyl alcohol. After the final immer- The eastern chipmunk, Tamias striatus, sion in absolute alcohol they were de- is a diurnal ground squirrel common to alcoholized in xylol and then embedded the eastern deciduous forests of North in Paraplast by gradual infiltration America (Hall and Kelson 1959). East- through a mixture of xylol and Paraplast ern chipmunks are solitary and territorial and finally Paraplast alone. The tissue as adults, and each occupies a burrow specimens were then sectioned at 10 n. system distinct from those of others Each fifth section from both the cranial (Yahner 1978). Mucous and sebaceous half of the dorsal tissue and the right oral glands have been described in the side of the anal tissue, and all sections of eastern chipmunk (Quay 1965), but the the caudal half of the dorsal tissue and presence of glands in other regions of the left anal tissue were mounted on slides, body have not been reported to our hydrated, and immersed in Bouin's fixa- knowledge. The social organization of tive. After 30 minutes, the slide prepa- T. striatus is similar to certain solitary rations were washed in running tap water species of Spermophilus (see Kivett et al and then stained by the rapid phospho- 1976, Yahner 1978), and anal, or perhaps tungstic acid-hematoxylin method. vaginal, secretations may be an important No dorsal glands were detected in xNote received 11 May 1978 and in revised fresh or fixed skins, either macroscopically form 26 July 1978 (#78-25). 2Present address: Department of Entomol- or with a dissecting microscope. Micro- ogy, Fisheries and Wildlife, University of scopic examination of the dorsal sections Minnesota, St. Paul, MN 55108. revealed no glands (mucous, sebaceous, 40 Ohio J. Sci. DORSAL AND ANAL GLANDS IN TAMIAS 41 or sudoriferous) either associated with ing season, are of minor importance for hair follicles or isolated from follicles. intraspecific communication in this spe- In the anal sections, numerous sebace- cies compared to other ground squirrels ous glands were observed in association (e.g. Spermophilus; Kivett et al 1976). with hair follicles around the anal orifice Anal glands in Tamias appear to be and in the entire perineal region (fig. 1). modified sebaceous glands, and the loca-

FIGURE 1. Typical section through the perineal region showing hair follicles and associated sebaceous glands. X100.

No sebaceous glands occurred laterad or tion of the glands largely corresponds to dorsad to these regions. In addition to those described in the Richardson ground sebaceous glands, aggregations of glandu- squirrel, S. richardsonii (Sleggs 1926). lar tissue were noted in the walls of the Anal glands in Tamias are a plausible anal canal and extending into the source of reproductive pheromones. The perineum. This glandular tissue was alveoli of the anal glands in our speci- observed between the external anal mens, which were sacrificed in early sphincter and the connective tissue layer December, however, seemed to be in a of the canal (fig. 2) and also extending a quiescent stage. Recrudescence of go- short distance craniad between the ex- nads and accessory reproductive struc- ternal and internal anal sphicters. Ducts tures in male eastern chipmunks does not lined by thick stratified squamous epi- begin until late December or January thelium opened near the anal orifice (Neff and Anthony 1963), and mating (fig. 3). does not occur until mid-February (Yah- Scent marking with dorsal regions of ner and Svendsen 1978). Examination the body was never observed in eastern of additional specimens at various times chipmunks during 2500 hours of field of the year would be necessary to de- study (Yahner 1978); thus, the absence termine whether or not maximal develop- of dorsal glands is not surprising. This ment of anal glands correlates with re- supports the contention that glandular productive condition and breeding ac- secretions, at least during the nonbreed- tivity. 42 RICHARD H. YAHNER ET AL Vol. 79

FIGURE 2. (upper) Obliquely longitudinal section through the anal canal, AC. A mass of glandular tissue, G, shows at extreme left center and another aggregation below and to the right of the larger aggregation. The external anal sphincter muscle, ES, appears in the lower left corner and in the upper right corner. Note the numerous hair follicles in cross section. A higher magnification would show an abundance of sebaceous glands attached to the hair follicles. X62. FIGURE 3. (lower) Section through a main duct of an anal gland. Note the thick stratified squamous epithelium lining the duct, and the pale sebaceous-type cells that may be discharging into the lumen, D, of the duct. Fibers of the external anal sphincter, ES, appear in the upper left corner. In this section, the anal canal is not shown but it was above the duct and a little to the right. X100. Ohio J. Sci. DORSAL AND ANAL GLANDS IN TAMIAS 43

Acknowledgment. Funds for this study were eastern chipmunk, Tamias striatus. Penn- provided by the Department of Zoology and sylvania Acad. Sci. 37: 64-70. Microbiology, Ohio University. W. Peterson Quay, W. B. 1965 Comparative survey of the prepared the photomicrographs. sebaceous and sudoriferous glands of the oral lips and angle in rodents. J. Mammal. LITERATURE CITED 46: 23-37. Dobroruka, L. J. 1972 Scent marking and courtship in Siberian chipmunks, Tamias Sleggs, G. F. 1926 The adult anatomy and sibiricus lineatus (Siebold 1824), with notes on histology of the anal glands of the Richardson the taxonomic relations of chipmunks (Mam- ground squirrel, Citellus richardsomi, Sabine. malia). Vest. Cs Spol. Zool. 36: 12-16. Anat. Rec. 32: 1-43. Eisenberg, J. P. and D. G. Kleiman 1972 Steiner, A. L. 1974 Body-rubbing, marking, Olfactory communication in mammals. Ann. and other scent-related behavior in some Rev. Ecol. Syst. 3: 1-32. ground squirrels (Sciuridae): a descriptive Hall, E. R. and R. Kelson 1959 The mammals study. Canadian J. Zool. 52: 889-906. of North America. Ronald Press, New York. Kivett, V. K., J. O. Murie and A. L. Steiner Yahner, R. H. 1978 The adaptive nature of 1976 A comparative study of scent-gland lo- the social system and behavior in the eastern cation and related behavior in some north- chipmunk, Tamias striatus. Behav. Ecol. western nearctic ground squirrel species Sociobiol. 3: 397-427. (Sciuridae): an evolutionary approach. Ca- and G. E. Svendsen 1978 Effects of nadian J. Zool. 54: 1294-1306. climate on the circannual rhythm of the Neff, W. H. and A. Anthony 1963 Seasonal eastern chipmunk, Tamias striatus. J. Mam- changes in the male reproductive tract of the mal. 59: 109-117.