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In the study, it was aimed to reveal the morphological, morphometric and histological characteristics of sinus interdigitalis found in the fore and hind feet of Konya merino sheep. For this purpose, the fore and hind feet of 10 Konya merino sheep, weighing between 44-79 kg, were used. Sinus interdigitalis were dissected out from the feet, and after morphometric measurements were made, morphological examinations were performed and photographed. The shape of the sinus interdigitalis, present in all the forefeet and hind feet, resembled a pipe consisting of neck and body. It was determined that the neck part was longer than the body at all feet. The inner surface of the gland was covered with hair, and there was more hair on the neck than on the body. The weight of the gland, body length and diameter, flexura, canal length and diameter were measured morphometrically. In the measurements made, it was determined that all the values of the forefeet were higher than the hind feet. In histological examination, it was found that the wall of the sinus interdigitalis consists of three layers: epidermis, dermis and fibrous capsule, and in the dermis, hair follicles, sebaceous glands, m. arrector pili and sweat glands were found.

Skin biopsy specimens of normal llama skin were examined histologically. Adnexal structures similar to those of most other domestic mammals included epitrichial sweat glands, sebaceous glands and arrector pili muscles. Unique features of normal llama skin included a very thick dermis with marked differences between superficial and deep dermis, prominent cutaneous vascular plexuses, unidentified cells with eosinophilic granules within the adventitia of the vascular plexuses, both simple and compound hair follicles, ‘metatarsal glands’, ‘interdigital glands’, footpad glands and the absence of eyelid tarsal glands.

Piloerection (goosebumps) requires concerted actions of the hair follicle, the arrector pili muscle (APM), and the sympathetic nerve, providing a model to study interactions across epithelium, mesenchyme, and nerves. Here, we show that APMs and sympathetic nerves form a dual component niche to modulate hair follicle stem cell (HFSC) activity. Sympathetic nerves form synapse-like structures with HFSCs and regulate HFSCs through norepinephrine, whereas APMs maintain sympathetic innervation to HFSCs. Without norepinephrine signaling, HFSCs enter deep quiescence by down-regulating cell cycle and metabolism while up-regulating quiescence regulators Foxp1 and Fgf18. During development, HFSC progeny secretes Sonic Hedgehog (SHH) to direct the formation of this APM-sympathetic nerve niche, which in turn controls hair follicle regeneration in adults. Our results reveal a reciprocal interdependence between a regenerative tissue and its niche at different stages and demonstrate sympathetic nerves can modulate stem cells through synapses-like connections and neurotransmitters to couple tissue production with demands.

Leiomyoma is a benign tumor of smooth muscle origin most common in areas of the body with abundant smooth muscle including the gynecologic, genitourinary, and gastrointestinal system. Leiomyoma outside of these locations is believed to arise from vascular smooth muscle and arrector pili muscles. Leiomyoma of an extremity is a rare diagnosis, especially when present in a digit of the hand due to the paucity of smooth muscle in this location. We report three cases of leiomyoma of a digit of the hand.

In this paper, we find effective feature values for skin texture as captured by a non-contact camera to monitor piloerection on the skin to estimate emotion. Piloerection is observed as goose bumps on the skin when a person is emotionally moved or scared. This phenomenon is caused by the contraction of the arrector pili muscles with the activation of the sympathetic nervous system. Piloerection changes skin texture, because of which we think it effective to examine skin texture to estimate the subject’s emotions. Skin texture is important in the cosmetic industry to evaluate skin condition. Therefore, we thought that it will be effective to evaluate the condition of skin texture for emotion estimation. Evaluations were performed by extracting effective feature values from skin textures captured by using a high-resolution camera, where these feature values should be highly correlated with the degree of piloerection. The results showed that the feature value “the standard deviation of short-line inclination angles in texture” was satisfactorily correlated with the degree of piloerection.

Cutaneous leiomyomas can be classified into three types according to the site of origin: piloleiomyoma, angioleiomyoma, and dartoic (genital) leiomyoma. It might be expected that leiomyomas are commonly found on the scalp because there are many arrector pili muscles and vessels. However, leiomyomas are actually rarely reported in the scalp. Recently, we observed a case of cutaneous leiomyoma in the scalp and present our experience along with a literature review.

OBJECTIVES To explore the capability of very high-frequency ultrasound (US; 50-71 MHz) to detect the normal morphologic characteristics of the hair follicles and tracts, sebaceous glands, Montgomery glands, apocrine glands, and arrector pili muscles. METHODS A retrospective study, approved by the Institutional Review Board, evaluated the normal US morphologic characteristics of the hair and adnexal structures in a database of very high-frequency US images extracted from the perilesional or contralateral healthy skin of 1117 consecutive patients who underwent US examinations for localized lesions of the skin and 10 healthy individuals from December 2017 to June 2018. These images were matched with their counterparts from the database of normal histologic images according to the corporal region. The Cohen concordance test and regional mean diameters of the hair follicles and adnexal structures were analyzed. RESULTS The normal hair follicles and tracts, sebaceous glands, Montgomery glands, apocrine glands, and arrector pili muscles were observed on US images and matched their histological counterparts in all the corporal regions. There was significant US concordance (κ = 0.82; P = .0001) among observers. Regional mean diameters (millimeters) of the hair follicles, sebaceous glands, and apocrine glands are provided. CONCLUSIONS The hair follicles and tracts, sebaceous glands, Montgomery glands, apocrine glands, and arrector pili muscles are detectable with very high-frequency US, including some regional and anatomic variants. Knowledge of their normal US appearances is a requisite for detecting subclinical changes, understanding the physiopathologic characteristics, and supporting the early diagnosis and management of common dermatologic diseases.

*Corresponding Author Email: jchandrapooja@gmail.com ABSTRACT AIM: The aim is to evaluate the significance moving our little finger without the ring finger, along with it in, Tamilnadu population. BACKGROUND: Most of the people cannot flex their minimus, without the rind finger, along with it, this occurs because of human anatomy. The muscle connected to the tendons for those fingers are close or connected to the same. The tendons and bones are usually connected for last two fingers. For most people it weakens as they grow, but it’s just a gene in they are family to have stronger connections of those tendons. [1] Other than arrector pili in the skin, fingers do not contain muscles. The flexor muscles, which are used to bend the fingers, are located in the palm and forearm. The muscle bulks that move each finger may be partly blended, and the tendons may be attached to each other by a net of fibrous tissue, preventing completely free movement. The extent of this can differ from person to person [2]. REASON: This study was conducted in order to know the significance of flexing the minimus without ring finger.

In the foetal springbok skin, identifiable melanocytes are present before colour patterns are established. These pigment cells fail to appear in the pouch and belly areas, indicating that these zones are piebald and not albinotic. Areas of regional colour differences are sharply separated. Their distinctiveness is caused by a discontinuous change in brightness of the hairy coat. This is due to a stepwise shift in the average quanta of melanin in the hairs. The pigment itself does not alter its colour from one colour-zone to another, but the density of the pigment particles merely changes. It is suggested that the steps could correspond to a discontinuous difference in tissue dosage, resulting perhaps from differing activation among multiple melanizing genes. Anatomical peculiarities of the pouch area and horn rudiment are descriptionbed. A proposal is made that hair slope is brought about by traction from mobile superficial fibroblasts. These cells travel preferentially in the direction of the greatest tissue strain. By dragging the papillary layer components along behind them, such as the hair buds and arrector pili muscles, the hair streams could arise. The tips of the hair shafts will then point away from each direction of greatest internal expansion, which the fibroblasts strive to cover.

The present investigation aimed to evaluate the histomorphometric features of the skin of the Iranian native sheep (Bakhtiari breed). A total of 24 apparently healthy Iranian Bakhtiari sheep, aged 1-2 years were analysed and categorised on the basis of sex (12 females and 12 males). Samples were taken as small pieces from different regions of the skin, fixed and stained with H&E. The quantitative evaluations of different regions of skin were carried out using lattice line graticule (5 × 5) and light microscopy. The Student t- test and one-way ANOVA were used to analyse the data and detect significant differences. Results showed that the volume densities of different histological structures varied between sexes and among the different regions. No significant differ - ence was observed in volume densities of sebaceous glands, arrector pili muscles and blood vessels, but the other parameters studied differed significantly among the regions. Except for the arrector pili muscle and connective tissue, the volume densities of other tissue structures were significantly affected by sex.

Leiomyosarcomas are rare malignant tumors of smooth muscles. Superficial leiomyosarcomas are classified into two subtypes depending on their location: cutaneous forms arise from the arrector pili muscles of hair follicles or dartos muscles of genital skin; subcutaneous forms arise from the smooth muscle lining of arterioles and veins in subcutaneous tissue. Superficial cutaneous leiomyosarcomas on the head are very rare. We report three cases of superficial cutaneous leiomyosarcoma, one localized on the face and two on the forehead.

In the classic model of the arrector pili (AP) muscle, each hair follicle is independently associated with a single AP muscle. Recently, new models have been proposed based on interpretations of serial histological cross-sectional images. The purpose of this study was to confirm the morphology of the AP muscle in relation to the follicular unit (FU) using quantitative three-dimensional (3D) reconstruction of serially sectioned images. Skin samples were obtained from the parietal region of the scalp, and processed using routine histological procedures. The serially sectioned slides were stained with Masson's trichrome. All the hairs and hair follicles of the FU exhibited some degree of slanting, with the single AP muscle slanted in the same direction. The distal portion of the AP muscle was divided into branches, as in a bronchial tree. There was branching in the single AP muscle present in the FU, and it was inserted into all the hair follicles of the FU either tightly or loosely. We suggest that the classic anatomy of the AP muscle must be modified with this new model, now confirmed by computer-based 3D reconstruction.

Cutaneous leiomyomas, which originate in the arrector pili muscles of the skin are rarely seen benign cutaneous tumors. Sometimes familial cutaneous and uterine leiomyomatosis can occur together, an autosomal dominant genetic condition called Reed syndrome or familial leiomyomatosis cutis et uteri. This disorder can be accompanied by malignancies, particularly by renal carcinoma. In this paper, two sisters with Reed syndrome are presented in view of the rarity of the disorder and good response to pregabalin therapy.

A time series reflecting human brain activities was detected by using a sensitive micro-acceleration · inclined-angle sensor composed of a CoSiB magnetostrictive amorphous wire connected to a CMOS IC circuit with a resolution of about 0.1 Gal and 0.2°. A small sensor head using a glass specimen of 0.16 mm thick, 3 mm wide, and 15 mm long to which were attached a CoSiB amorphous wire of 20 μm diameter and 5 mm length and an inertia mass of 0.1 g was fixed to the center of a subject’s forehead.The detected waveforms of the sensor output for subjects with both eyelids closed differ from the microvibration would be classified into the following four kinds of states:(1) An almost flat waveform indicates that the subject is in a resting state or a sleeping state.(2) Passively stressful states such as recalling sad memories, being obliged to perform an unpleasant task, or performing a mental calculation generate a large stepwise wave with some irregular pulsing waves.(3) Actively stressful states such as finding a good idea and focusing on inventing something are indicated by high-frequency pulsing waves.(4) Pleasant states such as recalling happy memories of childhood or thinking about a favorite hobby are indicated by rhythmical waves without pulses.These signals reflecting a subject’s mental and emotional states (which we call a mechano-encephalogram) are considered to be due to micro-deformation and acceleration of the measurement position with some movement of eyeball muscles, arrector pili muscles and muscles corrugator supercilii. Microvibrations of small amplitude were also detected.

Background: Encephalocraniocutaneous lipomatosis is usually associated with a peculiar type of fatty tissue nevus which represents a smoothly surfaced and hairless lesion involving the scalp. This disorder has so far not been recognized as a cutaneous entity. Objective: The purpose of this article is to describe the characteristic features of this nevus and to give it a name. Method: From the study of two cases and from a review of the literature we delineate the clinical and histopathological criteria of this disorder for which we propose the term ‘nevus psiloliparus’. This name is derived from the Greek words psilós = hairless and liparós = fatty, and describes the two most characteristic features of the disorder. Results: A comprehensive comparison shows that nevus psiloliparus can be distinguished from other types of fatty tissue nevi by clinical criteria such as localization on the scalp, a flat smooth surface and absence of hair follicles, by the histopathological feature of isolated arrector pili muscles and by the presence of associated extracutaneous features in the form of encephalocraniocutaneous lipomatosis. In particular, nevus psiloliparus can be separated from the Hoffmann-Zurhelle nevus that has so far never been observed in cases of encephalocraniocutaneous lipomatosis. Conclusion: The presently available data suggest that nevus psiloliparus represents a distinct cutaneous entity. Future clinical and genetic research should show whether this concept holds true.

Terminal hair follicles of the human scalp of all ages showed apoptotic pocket-like structures in the outer root sheath of the bulge area at anagen, but not telogen phase. The occurence of these hole structures was roughly estimated in 15% of anagen terminal hair follicles of the human scalp. The size of these apoptotic pockets was variable, ranging from pin hole-like spaces to larger structures filled with homogeneous black materials. These unusual variations were often co-localized with apoptotic degenerations and exclusively present in the presumptive bulge of anagen terminal hair follicles where arrector pili muscles were seen in the vicinity. In fact, these vacuolated structures tended to be present on the side where the major part of the arrector pili muscles anchored.

The arrector pili (AP) muscle was recently suggested to comprise one AP muscular unit inserted into all the hair follicles contained within the follicular unit (FU). This study investigated the presence of variations in AP muscular units associated with the FUs. Human cadaver scalp skin specimens were serially sectioned and stained with Masson's trichrome. Three-dimensional reconstructions of the serially sectioned images were analyzed on a computer, which revealed two types of variation in 20 FUs, one of which was the multiunit AP muscular structure, in which the AP muscular unit was inserted into two or more FUs.

The follicular proximal ends of arrector pili muscles anchor the bulge areas of human hair follicles. However, the location of the ends of these muscles towards the epidermis, especially the fine points of attachment, is not fully understood. Conventional serial sections of the scalp skin of a 12-month-old infant were examined. Most of the distal ends were situated in the upper dermis, while some seemed to be in close contact with the epidermal basal layers. In vertical sections of the scalp skin of 36-week-old fetus, double immunoenzyme staining showed a close topographic correlation between the epidermal ends of the arrector pili muscles and the epidermal and dermal Merkel cells. These findings allow speculation that fetal Merkel cells participate in the induction and alignment of arrector pili muscles.

Smooth muscle hamartoma (SMH) is a cutaneous malformation mainly composed of a disorganized proliferation of normal muscle fibers that arise from arrector pili. It usually presents as a single congenital lesion that frequently involves the back and the lower limbs. Unusual clinical presentations, such as atypical localizations, multiple disseminated lesions, and generalized forms have been rarely described. In 2001, Gualandri et al. reported the presence of multiple SMH in three members of the same family, namely two brothers and their mother. This is, as far as we know, the only familial case reported in the English literature. We herein describe a similar case affecting two siblings who presented with identical congenital lesions in the same location.

Potentially viable therapeutic approaches for Duchenne muscular dystrophy (DMD) are now within reach. Indeed, clinical trials are currently under way. Two crucial aspects still need to be addressed: maximizing therapeutic efficacy and identifying appropriate and sensible outcome measures. Nevertheless, the end point of these trials remains painful muscle biopsy to show and quantify protein restoration in treated boys. In this study we show that PMMA/N-isopropil-acrylamide+ (NIPAM) nanoparticles (ZM2) bind and convey antisense oligoribonucleotides (AONs) very efficiently. Systemic injection of the ZM2-AON complex restored dystrophin protein synthesis in both skeletal and cardiac muscles of mdx mice, allowing protein localization in up to 40% of muscle fibers. The mdx exon 23 skipping level was up to 20%, as measured by the RealTime assay, and dystrophin restoration was confirmed by both reverse transcription-PCR and western blotting. Furthermore, we verified that dystrophin restoration also occurs in the smooth muscle cells of the dorsal skin arrector pili, an easily accessible histological structure, in ZM2-AON-treated mdx mice, with respect to untreated animals. This finding reveals arrector pili smooth muscle to be an appealing biomarker candidate and a novel low-invasive treatment end point. Furthermore, this marker would also be suitable for subsequent monitoring of the therapeutic effects in DMD patients. In addition, we demonstrate herein the expression of other sarcolemma proteins such as alpha-, beta-, gamma- and delta-sarcoglycans in the human skin arrector pili smooth muscle, thereby showing the potential of this muscle as a biomarker for other muscular dystrophies currently or soon to be the object of clinical trials.

The multi-sections, which were stained by Fite method, of skin biopsies taken from twelve active BT cases were examined under the guidance of special stains for demonstration of nerve components. All cases were AFB positive. Bacilli were found in infiltrated nerves in 11 cases, of which, in 7 cases, bacilli were detected in nerve fragments within epithelioid cell granuloma. And bacilli were seen in arrector pili muscles in 2 cases. No bacilli were detected in other sites. Since the survival of M. leprae in nerves is one of the reasons causing relapse, this paper suggests that it would be better to treat active BT cases with multibacillary regimen recommended by WHO even though smear-negative.

Over the years, different kinds of hair transplantation have been compared in an attempt to overcome male pattern alopecia and, at the same time, maximize both survival and growth rates of grafted hair. Hair follicular transplantation, presented by Bernstein et al1 in 1995, is grounded on hair emerging from the scalp in a set of 1–4 (5 in some occasions) terminal hair follicles. These follicles, together with 1 (rarely 2) vellus follicles, the associated sebaceous lobules, the insertion of the arrector pili muscles, its neural and vascular plexuses, and the adventitial collagen, represent the follicular units (FUs).2 This whole structure must therefore be collected directly from the donor area during the harvesting procedure and then grafted into the recipient area. Hair micrografts that were originally designed to improve the frontal hair line by making it look more natural3,4 after hair transplantation also became useful in the grafting of eyebrow reconstruction5 (ie, after-burn injuries). Furthermore, several surgeons have been performing the so-called “megasession,” which consists in the transplantation of a large number of micrografts per session.6–8 A micrograft is composed of 1–2 hairs, surrounded by minimal interfollicular tissue, not necessarily corresponding to the naturally occurring FUs.2 With this study, we compared the survival and growth rate of FUs and conventional hair micrografts, in an in vitro system, to experimentally evaluate and elaborate on the differences between these 2 approaches in hair transplantation procedures.

Folliculitis is an inflammatory reaction in the superficial aspect of the hair follicle and can involve the follicular opening or the perifollicular hair follicles. The pilosebaceous unit of the follicle is divided into three compartments: the infundibulum (superficial part, outlined by the sebaceous duct), the isthmus (between the sebaceous duct and arrector pili protuberance), and the inferior segment (stem and hair bulb). This anatomical scheme forms the basis for any evaluation of the clinical manifestations of folliculitis. Most of the follicular conditions can be classified according to their anatomical location and histopathologic patterns. Clinically, the inflammation manifests as 1mm-wide vesicles, pustules, or papulopustules in acute cases; however, hyperkeratosis and keratotic plug formations are indicative of a chronic process. The presence of superficial pustules does not always imply an infectious origin, as there are many noninfectious types of folliculitis. In this review, we describe the different types of folliculitis based on their etiology, clinical manifestation, and treatment. We also discuss some newly described disorders and the latest information on their treatment.

Cutaneous smooth muscle is present in 3 separate locations: arrector pili muscles, blood vessel walls, and genital/areolar skin. Benign or malignant smooth muscle neoplasms may arise from each of these locations. This review discusses the pathogenesis, clinical manifestations, histologic findings, prognosis, treatment options, and controversial areas of cutaneous smooth muscle neoplasms. ( J Am Acad Dermatol 2002;46:477-90.) Learning objective: At the completion of this learning activity, participants should be able to discuss the pathogenesis, clinical manifestations, histologic findings, prognosis, and treatment options of cutaneous smooth muscle neoplasms.

Smooth muscle hamartoma is a cutaneous abnormality characterized by a disorganized proliferation of normal muscle fibers of arrector pili. Usually a single congenital hypertrichotic plaque involves the trunk and the extremities. Multiple lesions have rarely been reported in the literature. We describe three members of the same family with multiple skin-colored patches on the back and legs, histologically confirmed as smooth muscle hamartomas. To our knowledge this is the first report of multiple smooth muscle hamartomas in different members of the same family and quite interestingly involving the same skin site.

Cutaneous piloleiomyoma is a rare benign tumor of skin originating from skeletal muscle of arrector pili attached to hair follicle. It can be single or multiple, solitary piloleiomyoma are common over genitalia. Multiple cutaneous piloleiomyomas are rare and they can cause pain on exposure to cold or with emotional disturbance. The prognosis of cutaneous piloleiomyomas after surgical excision is good. Here, we present a rare case of generalized multiple cutaneous piloleiomyoma in a young male.

Arrector pili muscles have been assumed to attach to one side of the hair follicle, specifically the posterior wall of the bulge area. In this study, we demonstrated immunohistochemically that desminreactive arrector pili muscle, admixed with the connective tissue sheath, is present around the entire circumference of the vellus hair follicle.

Although knowledge of normal scalp anatomy, the hair follicle, and the dynamics of hair cycling is substantial, 1–3 the histopathology of male-pattern baldness (MPB), also called premature baldness or androgenetic alopecia, is uncertain. Textbook accounts are uninformative, 4,5 and controversies are plentiful. Disputes exist about matters that seem quite simple, for example, whether the sebaceous glands are enlarged or shrunken. There are also opposing views on the fate of the arrector pili muscles. All agree that hair follicles become progressively smaller (miniaturized), but whether there is an actual loss of follicles is in contention. Two important publications on various cutaneous aspects of aging do not even include chapters on hair. 6,7

• Congenital pigmented arrector pili hamartomas are unique malformations of epidermis and pilar apparatus usually appearing as localized, lightly pigmented, hairy plaques. Characteristic microscopic features include smooth-muscle proliferation similar to irregularly disposed arrectores pilorum, and slight elongation of epidermal rete with hypermelanosis of the basal unit. An otherwise normally developed child who had this hamartoma at birth is described in an attempt to clarify the relationship between pilar smooth-muscle hamartomas and Becker's melanosis. We propose that these two entities belong at different poles of the same developmental spectrum of hamartomatous change. ( Arch Dermatol 1985;121:1034-1037)

An interfollicular smooth muscle that spans the triad of hair follicles has been identified in the skin of the domesticated pig (Sus scrofa). This muscle has been previously noted by other investigators and identified as an arrector pili muscle. However, it cannot be interpreted as such for the following reasons: (1) It lies opposite the arrector pili muscle on the follicle; (2) the orientation of its fibers is perpendicular to those of the arrector pili; (3) the two muscles are not continuous; their attachments are different; and (4) contraction of the interfollicular muscle would have little effect on erection of the hairs. Based on structural evidence, it is postulated that upon contraction the muscle draws the base of the three aligned follicles together into a triangular conformation. In so doing, it may rotate the outer two follicles of the triad. Its specific functional role is unknown.

Detail histological studies were made of skin samples from seven specimens of Odocoileus hemionus columbianus collected in August in Monterey County, California. the preorbital sac was found to be relatively nonglandular and to contain primarily sloughed epidermal cells and mucoid (probably lacrymal) secretion. Interdigital glands are well developed in forefeet and hind feet of both sexes and contain enlarged sebaceous and sudoriferous glands. the metatarsal “gland” is a duplex organ consisting of (1) a central nonglandular keratinized ridge with high papulation, rich innervation, and modified vasculature, and (2) a peripheral haired and sudoriferous glandular zone. Tarsal glands are most remarkable histologically for the size of their arrector pili smooth muscles and the development of a dense elastic fiber lamina between papillary and reticular zones of the dermis. Sebaceous and sudoriferous glands are also enlarged in the tarsal glandular organ, but whether these or external urine deposits are the source of the social scent of the organ remains unknown. Caudal arrector pili and glandular enlargements of lesser magnitude are present also. Comparative differences and probable functional relations of these integumentary organs are discussed.

To the Editor.— Eruptive vellus hair cysts (EVHCs) were first reported by Esterly et al in 1977.1Since then, several cases have been described, two of them involving familial affectation, which suggests an apparent autosomal dominant inheritance.2,3 Although clinical findings may be variable in age of onset, localization, and evolution, histologic studies are distinctive, consisting in all cases of a small cyst located in the midcorium with a wall composed of several layers of squamous cells and a cavity containing laminated and amorphous keratinous material and vellus hairs. Occasionally, the cysts are in continuity with hair follicles1,4,5or arrector pili muscles,1,2and, in some cases, one or more sebaceous glands were seen near the cyst.6,7 We describe herein a case of EVHC with sebaceous glands within the cyst wall, similar to those seen in steatocystoma. Report of a Case.— A 22-year-old woman was examined for

Subauricular and rump glands of pronghorns (Antilocapra americana) collected during every month of the year, were examined histologically. In early spring the apocrine and sebaceous zones of the paired subauricular glands, which are found only in males, proliferate abruptly. These zones continue to enlarge and become highly secretory during the summer; they regress during the fall and are quiescent in December. During the peak of activity large sebaceous storage vesicles are present and copious amounts of secretory material occupy the apocrine lumina. Irregular clumps of cells that are associated with the apocrine tubules are numerous in summer and appear to be associated with apocrine secretory activity. The subauricular glands of castrated bucks are small and inactive compared to normal glands. Annual proliferation and regression of the subauricular glands follows similar activities of the testes. Thus, the cycle of activity in these glands is apparently controlled by gonadal hormones. Odors from the subauricular glands may serve for sex recognition, stimulation, and marking of territories. The paired rump glands consist of lobulated sebaceous units and coiled apocrine tubules that maintain limited secretory activity throughout the year. Contraction of large arrector pili muscles associated with hairs in the glands may cause accelerated secretion. The rump glands of normal males, females, and castrated males, are similar in all respects. Apparently these glands are not sexually influenced. The rump glands may serve for olfactory warnings in conjunction with the visual warnings of the white rump patch.

THE tarsal organ of deer of the genus Odocoileus is located, medially on the ankle (Fig. 1) and consists of sebaceous and apocrine sudoriferous glands as well as greatly enlarged arrector pili smooth muscle bundles1, which effect the erection of a long tuft of bright, stiff hairs. The hairs in the centre of the tuft are covered with a lipid film carrying the scent. The glands and urine are the possible sources of the tarsal scent. Tarsal organs are found only in tele-metacarpal deer (Odocoileinae); that is, in the New World genera Odocoileus, Blastocerus and Mazama, and in the Holarctic genera Alces and Rangifer2.