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An unusual lesion associated with obstruction of ectopic sebaceous glands of the retromolar mucosa is presented. Histologically, this was associated with mucus-producing and respiratory metaplasia of the sebaceous ducts that also demonstrated microcyst formation. Sebaceous glands were hyperplastic. A review of the literature did not reveal a similar published example.
The clinicopathological features of the scarring alopecia of discoid lupus erythematosus (DLE) were studied. Scarring alopecia was present in 34% of 89 patients with DLE and was associated with a prolonged disease course. More than half these patients had scalp involvement at the onset of the disease. There was a significant reduction in size of sebaceous glands in affected scalp. Perifollicular lymphocytic inflammation was maximal around the mid-follicle at the level of the sebaceous gland, which seems to be an important functional level in the follicle. There are changes in the expression of the matrix molecules, the proteoglycans, in the connective tissue sheath and the keratin intermediate filaments in the outer root sheath cells at this level in normal scalp and in diseased scalp. Loss of a population of mid-follicular stem cells may be important in the pathogenesis of scarring alopecia in DLE.
Nestin, a member of the sixth class of intermediate filament proteins, has long been known not only as a specific marker for central nervous system stem cells, but also as an indicator of the degree of neural stem cell differentiation. Immunohistochemical analysis showed nestin expression in the epidermis and the upper two-third of the hair follicle in non-balding human scalp skin, but not in the lower third of the follicle. Expression was very weak in the sebaceous gland. The level of nestin mRNA transcription was much higher in the bulge region of the follicle than in the sebaceous gland. These results show that the pattern of nestin expression is related to the differentiation of epidermal stem cells.
5 alpha-DHT is bound with a high affinity (Kd = 0.8 nM) and a limited capacity (80 fmol/mg proteins) in the cytosol of the preen gland of quails, an analogue of sebaceous glands. The complex can be precipitated by protamin-sulfate and is sedimented in the 8 S region after ultra-centrifugation in a sucrose gradient. The occurrence of this binding that exhibits the main properties of an androgen receptor, supports the use of the preen gland of quails as a tool for the study of the mechanism of action of androgens in birds and as a model for the study of the androgen control of sebaceous-like glands.
An encapsulated tumor measuring 8 cm was removed from the parotid gland in a 42-year-old man. The tumor had grown for about 5 years. The histopathological and immunohistochemical evaluation revealed a lymphadenoma without sebaceous differentiation of the epithelial component. The tumor consisted of exclusively solid epithelial islands and a lymphoid stroma with rare lymph follicles and abundant predominantly IgG plasma cells. The histogenesis of lymphadenomas is discussed in consideration of the differential diagnosis from Warthin's tumor and the data in the literature.
Phosphoinositide-specific phospholipase C (PLC) is a key enzyme in phosphoinositide turnover and is involved in a variety of physiological functions. Here we report that PLCdelta(1)-deficient mice undergo progressive hair loss in the first postnatal hair cycle. Epidermal hyperplasia was observed, and many hairs in the skin of PLCdelta(1)-deficient mice failed to penetrate the epidermis and became zigzagged owing to occlusion of the hair canal. Two major downstream signals of PLC, calcium elevation and protein kinase C activation, were impaired in the keratinocytes and skin of PLCdelta(1)-deficient mice. In addition, many cysts that had remarkable similarities to interfollicular epidermis, as well as hyperplasia of sebaceous glands, were observed. Furthermore, PLCdelta(1)-deficient mice developed spontaneous skin tumors that had characteristics of both interfollicular epidermis and sebaceous glands. From these results, we conclude that PLCdelta(1) is required for skin stem cell lineage commitment.
Human sweat and sebaceous glands were studied immunohistochemically with a monoclonal antibody recognizing a vasoactive intestinal polypeptide (VIP) receptor. The staining pattern correlated well with the known distribution of sympathetic VIP-containing nerves in the human skin. The luminal cell layer of the sweat gland ducts and some acinar cells of the secretory coil of eccrine sweat glands were the major sites of VIP receptor-like immunoreactivity. From these findings and the known pharmacological actions of VIP it is concluded that a major role of VIP released from sympathetic nerves in the skin is to regulate chloride reabsorption from the primary sweat at the ductal segment.
The skin of the giraffe has the same general histological structure as that of other mammals, but there are notable features. The skin is heavily pigmented with the epidermis, pilary canals, and the outer cell layer of the apocrine duct richly melanized. Furthermore, melanotic dendritic cells are frequently found in the sebaceous glands, the entire length of the external root sheath, and the secretory tubules of the apocrine glands. The thick skin has a papillary dermis that extends to just beneath the secretory coils of the apocrine glands and bulbs of hair follicles and an equally thick reticular layer below these structures. The hair follicles do not grow in clusters, and with some regional variations, have associated sebaceous glands, apocrine glands, and arrectores pilorum muscles. Only the large hairs have a prominent medulla. In such specialized regions as the eyelids, nose, and lips, the apocrine glands are surrounded by cholinesterase-reactive nerves but the glands on the general body surface are not. The only specialized nerve receptors are hair follicle end organs found on every hair of the eyelids, nose, and lips, but only rarely elsewhere.
A lesion presenting a typical histopathological picture of sebaceous epithelioma comprised three kinds of cells; immature, transitional, and mature cells corresponding to the components of the normal sebaceous gland. Melanocytes and melanosomes were absent. These findings clearly distinguished the tumor from basal cell epithelioma, and it was concluded that sebaceous epithelioma represents a primary neoplasm of the sebaceous gland. New observations on lipid droplet formation are made with regard to the glycogen-containing cytolysome - tentatively designated a Liposome - and membrane structures around the lipid droplet found in mature cells.
Previous studies have demonstrated that the skin is an important site of de novo sterol synthesis and that there is a sex difference in cutaneous sterologenesis with male animals synthesizing more sterols than females. The aim of the present study was to localize the major sites of sterol synthesis within the skin and to determine which of these sites accounted for the sex differences in sterologenesis. In male and female rats whose dermal and epidermal layers are separated by dithiothreitol treatment, the dermis is the major site of skin sterologenesis (males 86% of total, females 82% of total). Moreover, the sex difference in skin sterol synthesis is quantitatively localized primarily within the dermal layer (approximately 2.5-fold greater in the dermis of males). Sterol synthesis is also increased in the epidermis of males. To rule out the possibility that sebaceous gland production accounted for our observations, we treated animals with isotretinoin (13-cis-retinoic acid), a drug that suppresses sebaceous gland sebum production. Sterol synthesis in the skin of both male and female rats is not significantly altered by isotretinoin administration and the sex difference in skin sterologenesis is unaffected. To further localize the sites of sterol synthesis within the skin, studies of hairless mice whose skin was split by DTT were initiated. In hairless mice, DTT separates the epidermis into upper (stratum corneum and granulosum) and lower (basal and spinous cells) strata. The basal layer was separated from the dermis by gentle scraping. As in rats, the dermis is the chief site of sterol synthesis in the skin. In addition, the lower layer of the epidermis (basal and spinous cells) is also a very active site of sterologenesis, accounting for 20% of total skin nonsaponifiable lipid synthesis. The upper epidermis accounted for only a small portion of total skin synthesis. It is highly likely that the bulk of cutaneous sterol synthesis occurs in the pilosebaceous epithelium.
Two different monoclonal antibodies recognizing different epitopes were used to study the localization of luteinizing hormone/human chorionic gonadotrophin (LH/hCG) receptors in human skin. Immunolabelling was observed only in the epidermis and derived structures but not in the dermis. The basal, spinal and granular layers were stained, whereas no receptors were detected in the non-nucleated horny cells. In the growing (anagen) hair, immunostaining was found in the inner root sheath below the level of the sebaceous glands and in the outer root sheath above this level. In the resting (telogen) hair, only the latter staining was observed. In the sebaceous glands, only the thin cells close to the walls of the ducts were immunolabelled. In the eccrine sweat glands, the external clear cells were stained in the secretory portion of the gland, whereas only the cells close to the lumen were labelled in the ducts. The distribution of LH/hCG receptors was compared with that of steroidogenic enzymes (side chain cleavage cytochrome P450, adrenodoxin, 3-beta-hydroxy-5-ene steroid dehydrogenase Delta5-Delta4 isomerase, 17-hydroxylase cytochrome P450 and cytochrome P450 aromatase). Only partial overlaps were observed. The presence of LH receptor mRNA in the skin was confirmed by reverse transcription-polymerase chain reaction. Monoclonal antibodies raised against the human follicle-stimulating hormone receptor failed to detect the latter in the epidermal structures and in the dermis. The role of LH and hCG in skin modifications occurring during pregnancy and after the menopause is unknown. These hormones may possibly act by regulating steroidogenic enzymes or by modulating cell growth and differentiation.
In recent years, the hamster flank organ test has been frequently used to screen compounds for antiandrogenic activity. When used routinely, the diameter of the pigmented spot is used to evaluate the androgenic or antiandrogenic effect of the drug tested. In this article, it is shown that the pigmented spot and the sebaceous glands may respond to a quite different degree to hormonal stimuli, indicating that visual observation alone is insufficient for screening purposes. Determination of sebaceous gland sizes by histochemical techniques allows a better evaluation of androgenic or anti-androgenic effects.
The presence of sebaceous glands within the oral mucosa is not uncommon. Such Fordyce granules are frequently seen on the buccal mucosa and lips, as well as in the retromolar area, gingiva, and palate. Whereas sebaceous elements are rarely encountered on the tongue, three cases of ectopic sebaceous glands have been reported in association with apparently patent thyroglossal ducts. An interesting case of a previously unreported sebaceous choristoma of the thyroglossal duct is described.
Many lines of evidence indicate that the activity of sebaceous glands can be modulated by neuropeptides. Direct evidence in man, however, is still missing. We show that SZ95 sebocytes, an immortalized human sebaceous gland cell line, express receptors for alpha-melanocyte-stimulating hormone. Reverse transcription polymerase chain reaction with primers against the five melanocortin receptors and immunofluorescence studies using an antibody directed against a peptide corresponding to the amino acids 2-18 of the human melanocortin-1 receptor disclosed specific transcripts and immunoreactivity for melanocortin-1 receptor in these cells. Melanocortin-1 receptor expression was confirmed in sebocytes of normal human skin by immunohistochemistry. In contrast, no immunostaining for the melanocortin-5 receptor could be detected in sebocytes in situ, in accordance with the lack of specific transcripts for this melanocortin receptor in SZ95 sebocytes. As cytokines play an important role in the recruitment of inflammatory cells in acne and related disorders and alpha-melanocyte-stimulating hormone exerts immunomodulatory effects in many other cell types, we investigated the effect of alpha-melanocyte-stimulating hormone on interleukin-8 secretion by SZ95 sebocytes. Treatment with interleukin-1beta resulted in a marked increase in interleukin-8 release that was partially blocked by coincubation with alpha-melanocyte-stimulating hormone in a dose-dependent manner. Taken together, we show here that the melanocortin-1 receptor is expressed in vitro and in situ in human sebocytes. By modulating interleukin-8 secretion, alpha-melanocyte-stimulating hormone may act as a modulator of inflammatory responses in the pilosebaceous unit.
Skin comprises many cell types that are characterized by high biosynthetic activity and increased energy turnover. The creatine kinase system, consisting of creatine kinase isoenzymes and creatine transporter, is known to be important to support the high energy demands in such cells. We analyzed the presence and the localization of these proteins in murine and human skin under healthy and pathologic conditions, using immunoblotting and confocal immunohistochemistry with our recently developed specific antibodies. In murine skin, we found high amounts of brain-type cytosolic creatine kinase coexpressed with lower amounts of ubiquitous mitochondrial creatine kinase, both mainly localized in suprabasal layers of the epidermis, different cell types of hair follicles, sebaceous glands, and the subcutaneous panniculus carnosus muscle. With exception of sebaceous glands, these cells were also expressing creatine transporter. Muscle-type cytosolic creatine kinase and sarcomeric mitochondrial creatine kinase were restricted to panniculus carnosus. Immediately after wounding of murine skin, brain-type cytosolic creatine kinase and a creatine transporter-subspecies were transiently upregulated about 3-fold as seen in immunoblots, whereas the amount of ubiquitous mitochondrial creatine kinase increased during days 10-15 after wounding. Healthy and psoriatic human skin showed a similar coexpression pattern of brain-type cytosolic creatine kinase, ubiquitous mitochondrial creatine kinase, and creatine transporter in this pilot study, with creatine transporter species being upregulated in psoriasis.
gamma-glutamyl transpeptidase activity was monitored in cycling mice by histologic localization and biochemical assay. Our objective for this study is to establish the relationship between gamma-glutamyl transpeptidase activity and hair growth and to determine whether its activity can be correlated to induced hair growth. In cycling mouse skin, gamma-glutamyl transpeptidase activity is pronounced during anagen and greatly diminished during telogen. In the skin, the enzyme is present exclusively in the outer and inner root sheaths of hair follicles. gamma-glutamyl transpeptidase is limited to the follicle below the level of the sebaceous gland and is completely absent in the follicle above the sebaceous gland level. During anagen, the outer root sheath in the hypodermis is intensely positive for gamma-glutamyl transpeptidase activity whereas the hair matrix cells and dermal papillar are negative. The inner root sheath above the bulb shows distinctive membrane staining for gamma-glutamyl transpeptidase. gamma-glutamyl transpeptidase activity can be seen to vary only in cycling follicles. Inducing anagen by plucking hair shafts results in an increase in gamma-glutamyl transpeptidase activity directly correlated to hair regrowth. In a similar manner, mice were plucked and treated with a daily dose of 2% minoxidil. A slight difference in cycle lengths was seen in animals treated with minoxidil when compared to vehicle control. Minoxidil treatment may cause an early initiation of anagen, but both the minoxidil-treated skin and the vehicle-treated skin entered telogen at the same time. Together, these studies indicate that gamma-glutamyl transpeptidase is a specific marker of anagen in growing hair.
A 5-year-old rabbit with generalized scaling is presented. Multiple skin scrapings and acetate tape impressions were negative for mites and Malassezia. Culture for dermatophytes was also negative. Skin biopsies showed similarities with sebaceous adenitis described in rabbits (absence of sebaceous glands, perifollicular lymphocytic infiltrate at the level of the absent sebaceous glands, lymphocytic mural folliculitis, interface dermatitis). The owners refused any treatment and 2 months later the rabbit was euthanized due to anorexia. At necropsy a mass was found in the anterior mediastinum. Histopathology confirmed a diagnosis of thymoma. A possible paraneoplastic skin disease was suspected, based on similarities with thymoma-associated exfoliative dermatitis in cats.
Conflicting impressions regarding the anatomy of Montgomery's areolar tubercle exist. Twelve modified radical mastectomy specimens provided 1,536 serial sections of areolar tubercles. In 34 of 35 tubercles (97%), a mammary lactiferous duct was associated with a sebaceous apparatus. This lactiferous duct ascended from deeper mammary parenchyma and entered the sebaceous gland. Histopathologic changes identified included featured of fibrocystic disease, atypical intraductal hyperplasia, and carcinoma in situ. Because the areolar tubercle has two components, a sebaceous gland and a mammary duct arising from deeper breast parenchyma, diseases of the breast may also involve the areola independent of papilla-nipple involvement. Areolar preservation may best be used with the knowledge that diseases underlying the areola may also involve the areola.