Morphology and glycoconjugate histochemistry of the palpebral glands of the adult newt, Notophthalmus viridescens.

The eyelids of the newt were studied in 10 microns serial paraffin and 1-2 microns plastic sections using standard histological stains and special stains for glycoconjugates. The eyelids contain four different glands. Simple acinar serous and simple acinar mucous glands occur in the skin; unicellular mucous glands occur in the conjunctiva; and convoluted tubular seromucous glands are present in connective tissue beneath the conjunctiva. The first two are identical to cutaneous glands found elsewhere on the head and body. The simple acinar serous glands are surrounded by myoepithelial cells and release their secretion, which is composed largely of proteins with minimal glycoconjugate content, by a holocrine mechanism. The secretory product of the simple acinar mucous glands is composed of neutral glycoconjugates with a minor content of acidic glycoconjugates; the mucin exhibits strong PAS and PAPD staining and weak staining by AB and PAPS methods. The unicellular conjunctival mucous glands secrete both neutral and acidic glycoconjugates as shown by positive reactions with PAS, PAPD, PAPS, and AB methods. Convoluted tubular seromucous glands in the ventral eyelid synthesize both proteins and neutral glycoconjugates. The mucous secretions of the conjunctival glands probably provide lubrication and protection for the cornea.     

Comparative responsiveness of supracaudal and other sebaceous glands in male and female guinea pigs to hormones

Different types of sebaceous glands in guinea pigs were chosen to study their comparative responsiveness to steroid hormones. Glands selected were (1) Sebaceous glands associated with rudimentary hair in the supracaudal gland; (2) Free sebaceous glands of the nipple; (3) Sebaceous glands associated with the hair. The results showed distinct differences in sensitivity among these different sebaceous glands and according to the sex of the experimental animal. The most responsive of the glands in males was the supracaudal gland; in the female the most responsive glands were the sebaceous glands of the nipple. Sebaceous glands associated with normal hair were relatively insensitive to changes in hormonal level. In all cases testosterone propionate was more potent in stimulating any of the sebaceous glands than progesterone. After gonadectomy, various sebaceous glands showed unequal states of depletion due to the different rates of differentiation and disintegration of their cells into sebum.     

Thematic review series: Skin Lipids. Sebaceous gland lipids: friend or foe?

Sebaceous glands are intriguing glands that are found throughout the human body except on the palms of the hands and soles of the feet. The true function of these glands has yet to be determined, but there are several theories, including antioxidant effects, antibacterial effects, and transport of pheromones. Sebaceous glands produce lipids that are involved in the pathogenesis of one of the most prevalent diseases of adolescence, acne. Although the majority of lipids produced by the sebaceous gland are also produced in other areas of the body, there are two that are characteristic of the sebaceous gland, wax esters and squalene. This review seeks to present an update on the physiology of the sebaceous glands, with particular emphasis on the production of sebaceous lipids.     

Evolutionary origins of the mammary gland

Because the mammary gland has no known homologue among the extant reptiles, attempts to reconstruct its evolution must focus on evidence from living mammals. Of the numerous structures that have been hypothesized to have given rise to the mammary gland, only three remain as plausible progenitors: sebaceous glands, eccrine glands and apocrine glands. Ancestral mammary glands are usually assumed to have produced a copious watery secretion like that of human eccrine sweat glands. However, in terms of anatomy, physiology, development and topographical distribution, mammary glands are more similar to apocrine and sebaceous glands than to typical eccrine glands. Nevertheless, each of the three populations of cutaneous glands exhibit specializations unlikely to be primitive for the mammary gland. The mammary gland either predated full differentiation of mammalian cutaneous glands or, more probably, evolved as a neomorphic mosaic that combined the properties of apocrine and sebaceous glands. Consequently, ancestral, prototypic lacteal glands may have had the capacity to synthesize and secrete small amounts of organic substances, as do sebaceous and apocrine glands of living mammals.     

Cellular dynamics of the outer layers of the hair follicle of fine-wool sheep during the phase of stable hair growth

The structure, origin, and migration of outer sheath cells of the hair follicles of domestic sheep were studied by electron microscopic, autoradiographic, and histochemical (glycogen) methods in order to understand the role of this layer in hair morphogenesis. We demonstrated that the cells of the outer layers of the outer sheath interpose into the inner “companion” layer of the outer sheath. Although this process takes place all along the hair follicle from the lower bulb up to the sebaceous glands orifices, it mainly takes place over the bulb. Labeled cells interposed into the companion layer reach sebaceous glands orifices more than 24 h faster than labeled cells of the inner sheath and hair, because these cells included the label not in the bulb cambium (as hair and inner sheath) but over the bulb, and from this point they start movement. Interposition of cells into the companion layer must cause increase of its volume and additional volume supposed to be led away into the pillar canal around the hair near the sebaceous glands orifices. This can provide the mechanism of the hair and inner sheath promotion to sebaceous gland orifices.     

Lipidomics of human Meibomian gland secretions: Chemistry, biophysics, and physiological role of Meibomian lipids

Human Meibomian gland secretions (MGS) are a complex mixture of diverse lipids that are produced by Meibomian glands that are located in the upper and the lower eyelids. During blinking, MGS are excreted onto the ocular surface, spread and mix with aqueous tears that are produced by lachrymal glands, and form an outermost part of an ocular structure called “the tear film” (TF). The main physiological role of TF is to protect delicate ocular structures (such as cornea and conjunctiva) from desiccating. Lipids that are produced by Meibomian glands are believed to “seal” the aqueous portion of TF by creating a hydrophobic barrier and, thus, retard evaporation of water from the ocular surface, which enhances the protective properties of TF. As lipids of MGS are interacting with underlying aqueous sublayer of TF, the chemical composition of MGS is critical for maintaining the overall stability of TF. There is a consensus that a small, but important part of Meibomian lipids, namely polar, or amphiphilic lipids, is of especial importance as it forms an intermediate layer between the aqueous layer of TF and its upper (and much thicker) lipid layer formed mostly of very nonpolar lipids, such as wax esters and cholesteryl esters. The purpose of this review is to summarize the current knowledge on the lipidomics of human MGS, including the discussions of the most effective modern analytical techniques, chemical composition of MGS, biophysical properties of Meibomian lipid films, and their relevance for the physiology of TF. Previously published results obtained in numerous laboratories, as well as novel data generated in the author’s laboratory, are discussed. It is concluded that despite a substantial progress in the area of Meibomian glands lipidomics, there are large areas of uncertainty that need to be addressed in future experiments.     

Histomorphology of preorbital gland in territorial and non-territorial male blackbuck Antelope cervicapra, a critically endangered species

The preorbital gland is a specialized dermal gland of antelopes which plays an important role in territorial marking behavior and pheromonal communication. To our knowledge, there is little information available on the role of preorbital gland marks in Indian antelopes (blackbucks). Males are seen averting the gland during behavioural display and territorial marking but the functional aspect of this gland has not been examined. Hence, the aim of this study was to describe the histomorphology of the preorbital gland in territorial and non-territorial male blackbucks to determine its morphology and secretory function. The results showed that the preorbital gland is composed of modified sebaceous and apocrine glands. The apocrine gland is lined by simple cuboidal epithelial cells; the serous parts of the secretory products are often seen in the apical portions of the cells. The myoepithelial cells contain actin filaments lying on the basal membranes of the apocrine gland. There are some considerable histological changes in the presence of the sebaceous and apocrine glands in territorial males in comparison to non-territorial males. The following histological changes associated with occurrence of the sebaceous and apocrine glands have been observed in territorial and non-territorial male blackbucks: (1) increase of size of sebaceous and apocrine glands and (2) increase in density of sebaceous and apocrine glands in territorial males compared to non-territorial males. It is suggested that the higher development (i.e., size) and density of sebaceous and apocrine glands in territorial males could depend on hormone production (i.e., testosterone). Based on the histological observation and the role of sebaceous and apocrine glands in the preorbital gland supported by literature, it is possible to conclude that both territorial and non-territorial blackbuck males may produce pheromonal substances through preorbital gland (secretion) for olfactory communication.     

CHALONE CONTROL OF MITOTIC ACTIVITY IN SEBACEOUS GLANDS

Extracts of skin with sebaceous glands contain a substance which inhibits mitotic activity in sebaceous glands both in vivo and in vitro. This substance is neither the epidermal chalone nor the melanocyte chalone, both of which are also present in skin extracts. However, it resembles these other chalones in that it is water soluble, is precipitated by ethanol, is activated by the two stress hormones adrenalin and hydrocortisone, and is not species specific. It is present within the sebaceous glands, and it is evidently a sebaceous gland chalone.     

Detection of Hepatoid Glands and Distinctive Features of the Hepatoid Acinus

In the 1920s–1930s, skin glands of a new type, hepatoid glands, were described in 13 mammal species (Rodentia, Canidae, and Bovidae). The hepatoid glands resemble sebaceous glands in their morphology, bur radically differ from them in specific structure of the acinus and another type of secretion. Later, these data either could not be confirmed or were considered insignificant and the hepatoid glands were described as modified sebaceous glands, glands with uncertain function, or modifications of epidermis. Based on the studies of various hepatoid glands in 22 species of Carniviora and Artiodactyla, the authors described in detail the characteristic features of the hepatoid acinus, which allow a precise discrimination of hepatoid and sebaceous glands. Extracellular secretory canaliculi have been described in the hepatoid glands, as well as the richness of hepatoid glands in protein, distribution of hydrophobic lipids in certain hepatoid glands, and formation of excretory ducts and cysts. The hepatoid glands are a source of great amounts of protein secreted in the merocrine way; the secretory substance of some of these glands has a strong odor.     

Seasonal sebaceous patch in the nectar-feeding bats Leptonycteris curasoae and L. yerbabuenae (Phyllostomidae: Glossophaginae): phenological, histological, and preliminary chemical characterization

Many species of bats secrete a wide variety of substances, frequently associated with olfactory communication. We characterized a seasonal phenomenon of dorsal sebaceous secretion in the Cura?aoan long-nosed bat, Leptonycteris curasoae, in Venezuela, and the lesser long-nosed bat, Leptonycteris yerbabuenae, in Mexico. The phenology of the sebaceous patch was determined, a histological analysis of the affected area was conducted using specimens of L. curasoae from Venezuela, and finally, a preliminary chemical characterization of the substance secreted was performed combining histochemical techniques with gas chromatography and mass spectrometry analyses. The sebaceous patch was detected exclusively in male adult specimens. Individuals presenting it had a variable area of fur covered with a fatty and odoriferous substance at the level of the interscapular zone. Occurrence of the sebaceous patch was cyclical and coincided with the mating season in Venezuela and Mexico. The following histological changes associated with occurrence of the patch were observed: increase of epidermis thickness and decrease of dermis and hypodermis thicknesses, increase in density of sebaceous glands, increase of percentage of skin covered by sebaceous glands, increase of size of sebaceous glands previous to secretion followed, and increase of the sebum volume within sebaceous glands previous to secretion. Several compounds tentatively identified as fatty acids, cholestanes and cholesterol were present in the sebaceous secretion. Based on the evidence obtained, we hypothesize that the sebaceous patch could be involved in olfactory communication, possibly related to mating behavior in these bats.     

Characterization of Hair Follicle Development in Engineered Skin Substitutes

Generation of skin appendages in engineered skin substitutes has been limited by lack of trichogenic potency in cultured postnatal cells. To investigate the feasibility and the limitation of hair regeneration, engineered skin substitutes were prepared with chimeric populations of cultured human keratinocytes from neonatal foreskins and cultured murine dermal papilla cells from adult GFP transgenic mice and grafted orthotopically to full-thickness wounds on athymic mice. Non-cultured dissociated neonatal murine-only skin cells, or cultured human-only skin keratinocytes and fibroblasts without dermal papilla cells served as positive and negative controls respectively. In this study, neonatal murine-only skin substitutes formed external hairs and sebaceous glands, chimeric skin substitutes formed pigmented hairs without sebaceous glands, and human-only skin substitutes formed no follicles or glands. Although chimeric hair cannot erupt readily, removal of upper skin layer exposed keratinized hair shafts at the skin surface. Development of incomplete pilosebaceous units in chimeric hair corresponded with upregulation of hair-related genes, LEF1 and WNT10B, and downregulation of a marker of sebaceous glands, Steroyl-CoA desaturase. Transepidermal water loss was normal in all conditions. This study demonstrated that while sebaceous glands may be involved in hair eruption, they are not required for hair development in engineered skin substitutes.     

The skin of primates. XLI. The skin of the silver marmoset—Callithrix (= Mico) Argentata

The skin of the silver marmoset, Callithrix (= Mico) argentata Linnaeus, has many outstanding characteristics. The unusually thin epidermis and dermis are generally devoid of melanotic melanocytes. The surface of the interramal gular region is peppered with small, elevated papillae; that of the corpus penis is characterized by keratinized, proximally directed hollow spines in whose cavities are organized nerve end-organs and capillary loops. Cholinesterase-reactive papillary nerve end-organs and Meissner corpuscles populate all volar friction surfaces. A highly vascular dermis and subcutaneous fat pad partially contribute to the characteristic rubicund color of the face, external ears, and anogenital region. Many body surface hairs are accompanied by the classic Haarscheibe of Pinkus. Sinus hairs are plentiful; a circumscribed vibrissa-bearing eminence is located on the ventral ulnar aspect of each wrist. Alkaline phosphatase-positive, stellate-shaped cells are found on the outer root sheath and epithelial sac of active and quiescent hairs in all cephalic regions; such cells are not argyrophilic, aurophilic, or osmiophilic. Hairs grow in linear perfect sets of 3 to 5 follicles; they do not grow singly on the cheek. Large sebaceous glands contain alkaline phosphatase in their peripheral acini; extensive fields of gigantic multilobular sebaceous glands contribute to the distinct, opaque-white color of the scrotal skin. Numbers of apocrine sweat glands are diminished in cephalic regions but one gland occurs with each hair follicle in the axilla, scrotum, suprapubic region, and ulnar eminence. Relatively avascular eccrine sweat glands are confined to the volar friction surfaces. Their secretory coils contain sporadically distributed glycogen and phosphorylase and surrounding nerves are much more reactive for acetyl- than butyrylcholinesterase.     

Morphological, histochemical and immunohistochemical characterization of secretory production of the ciliary glands in the porcine eyelid

In addition to performing general histology and cytology of the ciliary glands of the miniature pig, we studied the localization of glycoconjugates and beta-defensins in these glands with the use of carbohydrate histochemical and immunohistochemical methods. The secretory cells of the glands were equipped with non-homogeneous secretory granules, a well-developed Golgi apparatus and rough endoplasmic reticulum. The secretory epithelium and luminal secretion of the glands contained large amounts of neutral and acidic glycoconjugates with various saccharide residues (alpha-L-Fuc, beta-D-Gal, alpha-D-GalNAc and sialic acid). The sebaceous glands and tarsal glands also exhibited positive reactions to most of the histochemical methods. Additionally, the antimicrobial peptide group of beta-defensins was demonstrated to be products of the ciliary glands, as well as the sebaceous glands and tarsal glands. The results obtained are discussed with regard to the specific function of the ciliary glandular secretions. These secretory products may be related to the moistening and general protection of the skin surface of the eyelid and ocular surface.     

Alterations of irisin concentrations in saliva and serum of obese and normal-weight subjects,before and after 45 min of a Turkish bath or running

The purpose of this study was to ascertain (1) whether human saliva contains irisin and whether its level correlates with serum irisin concentration, (2) whether salivary glands, eccrine glands and sebaceous glands in human skin produce irisin, (3) how the changes in saliva and serum irisin concentrations after the Turkish bath at 47 ± 3 °C compare with the changes caused by moderate exercise in obese and normal weight subjects. Seven obese male subjects and seven normal weight subjects were enrolled for Turkish bath. Seven obese male subjects and seven normal weight subjects were also enrolled for moderate outdoor exercise, and thirteen male normal weight subjects neither exercised nor showered at the Turkish bath. From each participant, 1.5 ml of saliva and 5 ml blood were collected simultaneously before and after the moderate exercise and Turkish bath. Salivary glands and eccrine and sebaceous glands in the skin were screened immunohistochemically for irisin while serum and saliva irisin were measured with an ELISA. Submandibular glands, eccrine glands and sebaceous glands in the human skin showed strong irisin immunoreactivity. Human saliva contained irisin and its level was significantly higher than the serum levels in both obese and normal weight subjects. However, irisin concentrations were more markedly increased in both saliva and serum samples from subjects who had showered at a Turkish bath than in obese subjects who had exercised or in normal weight subjects. Human submandibular glands, eccrine sweat glands and sebaceous glands synthesize irisin.     

Aspects of glycoconjugate production and lysozyme- and defensins-expression of the ceruminous glands of the horse (Equus przewalskii f. dom.)

The distribution of complex glycoconjugates and antimicrobial substances in the ceruminous glands of the horse (Equus przewalskii f. dom., type: pony) was studied using carbohydrate histochemical and immunohistochemical methods. The epithelial cells and luminal secretion of these glands exhibited considerable amounts of glycoconjugates with various saccharide residues, such as alpha-D-mannose, alpha-L-fucose, beta-D-galactose, beta-N-acetyl-D-glucosamine and sialic acid, including O-acetylated sialic acid. Several sugars (alpha-D-mannose, alpha-L-fucose, and beta-D-galactose) were also detectable in the secretion of sebaceous glands present. Additionally, lysozyme and the peptide group of beta-defensins are demonstrated as products of the apocrine ceruminous glands and sebaceous glands. The results obtained are discussed with regard to the functional significance of the glandular secretions. It is suggested that the complex carbohydrates, lysozyme and beta-defensins found in the ceruminous gland secretions are involved in the function of cerumen as a general antimicrobial protective agent in the external auditory canal.     

大仓鼠胁腺的发育及性别差异

通过对繁殖期雌雄大仓鼠胁腺重的比较研究发展雌雄鼠的胁腺重和体重分别存在正相关关系,非成年雌雄大仓鼠的胁腺重无显著性别差异,成年雄性大仓鼠的胁腺显著重于成年雌鼠,通过石蜡切片发现,雄鼠胁腺的皮脂细胞显著于雌鼠,对胁腺分泌物进行了气相色谱分析发现,雌雄胁腺分泌物的化学成分的种类和数量存在明显差异,本文从胁腺的形态,组织结构和化学成分三个方面初步揭示了胁腺在繁殖期具有性别别功能的机制。