Comparative studies of the ultrastructure of the sebaceous gland

Three-dimensional reconstructions and ultrastructural evidence on the sebaceous glands of man and domestic animals indicate that sebum is produced from a column of developing and degenerating cell populations derived from peripheral progenitor cells at the base of the lobe in a manner analogous to hair growth. The remainder of the peripheral cells apparently have no direct involvement with sebocyte production; those towards the neck of the gland contribute keratin to the secretory product.     

VAMP8/endobrevin as a general vesicular SNARE for regulated exocytosis of the exocrine system

The molecular mechanism governing the regulated secretion of most exocrine tissues remains elusive, although VAMP8/endobrevin has recently been shown to be the major vesicular SNARE (v-SNARE) of zymogen granules of pancreatic exocrine acinar cells. In this article, we have characterized the role of VAMP8 in the entire exocrine system. Immunohistochemical studies showed that VAMP8 is expressed in all examined exocrine tissues such as salivary glands, lacrimal (tear) glands, sweat glands, sebaceous glands, mammary glands, and the prostate. Severe anomalies were observed in the salivary and lacrimal glands of VAMP8-null mice. Mutant salivary glands accumulated amylase and carbonic anhydrase VI. Electron microscopy revealed an accumulation of secretory granules in the acinar cells of mutant parotid and lacrimal glands. Pilocarpine-stimulated secretion of saliva proteins was compromised in the absence of VAMP8. Protein aggregates were observed in mutant lacrimal glands. VAMP8 may interact with syntaxin 4 and SNAP-23. These results suggest that VAMP8 may act as a v-SNARE for regulated secretion of the entire exocrine system.     

Immunohistochemical localization of epidermal growth factor in rat and man

Epidermal growth factor (EGF) is a peptide which stimulates cell mitotic activity and differentiation, has a cytoprotective effect on the gastroduodenal mucosa, and inhibits gastric acid secretion. The immunohistochemical localization of EGF in the Brunner's glands and the submandibular glands is well documented. The localization of EGF in other tissues is still unclarified. In the present study, the immunohistochemical localization of EGF in tissues from rat, man and a 20 week human fetus were investigated. In man and rat, immunoreaction was found in the submandibular glands, the serous glands of the nasal cavity, Brunner's glands of the duodenum, the Paneth cells of the small intestine, and the tubular cells of the kidney. In the fetus EGF was found in the kidney and in the intestinal Paneth cells. Antisera raised against rat submandibular EGF did not recognize EGF in human tissues, whereas antisera against human urinary EGF worked in rat as well as man. EGF was found only in cells with an exocrine function.     

The evolution of food-producing glands in eusocial bees (Apoidea,Hymenoptera)1

A food-producing role for cephalic exocrine glands has arisen independently in both taxa of highly eusocial bees, Apis and Meliponini. With several exceptions, there is little evidence that food is produced by glands of solitary bees or by most bees at lower levels of sociality. We suggest that this association with sociality is due to four adaptive features of these glands: (1) food from the glands allows feces from queens and larvae to have a small volume, (2) the queen's fecundity can be increased, (3) nutrient recovery via cannibalism can be facilitated, and (4) rearing of emergency replacement queens is accelerated. Acceleration of the rearing of other castes and of queens in the normal process of colony fission is not clearly an advantage ascribed to these glands. Trophic eggs produced by meliponine colony workers are analogous to the secretions from food-producing glands in Meliponini and Apis workers.     

Immunohistochemical localization of epidermal growth factor in rat and man

Summary Epidermal growth factor (EGF) is a peptide which stimulates cell mitotic activity and differentiation, has a cytoprotective effect on the gastroduodenal mucosa, and inhibits gastric acid secretion.The immunohistochemical localization of EGF in the Brunner's glands and the submandibular glands is well documented. The localization of EGF in other tissues is still unclarified.In the present study, the immunohistochemical localization of EGF in tissues from rat, man and a 20 week human fetus were investigated. In man and rat, immunoreaction was found in the submandibular glands, the serous glands of the nasal cavity, Brunner's glands of the duodenum, the Paneth cells of the small intestine, and the tubular cells of the kidney. In the fetus EGF was found in the kidney and in the intestinal Paneth cells.Antisera raised against rat submandibular EGF did not recognize EGF in human tissues, whereas antisera against human urinary EGF worked in rat as well as man. EGF was found only in cells with an exocrine function.     

Queen Specific Exocrine Glands in Legionary Ants and Their Possible Function in Sexual Selection

The colonies of army ants and some other legionary ant species have single, permanently wingless queens with massive post petioles and large gasters. Such highly modified queens are called dichthadiigynes. This paper presents the unusually rich exocrine gland endowment of dichthadiigynes, which is not found in queens of other ant species. It has been suggested these kinds of glands produce secretions that attract and maintain worker retinues around queens, especially during migration. However, large worker retinues also occur in non-legionary species whose queens do not have such an exuberance of exocrine glands. We argue and present evidence in support of our previously proposed hypothesis that the enormous outfit of exocrine glands found in dichthadiigynes is due to sexual selection mediated by workers as the main selecting agents.     

On the expression of cytokeratins and their distribution in some rabbit gland tissues.

The composition and distribution of cytokeratins were studied in a series of exocrine and endocrine glands in the rabbit, by means of anti-human monoclonal antibodies. Rabbit cytokeratins are known to be homologous to those in man, and their in situ distribution was also found to be similar. In acinic cells of the exocrine glands, only cytokeratins 8 and 18 were detected, whereas in ductal cells 1, 5, 10, 11 and 13, 19 were also present. The myoepithelial cells surrounding acini and basal duct cells were stained with the antibodies directed against cytokeratins 13 and 1, 5, 10, 11. Among the endocrine glands, a higher reactivity was observed in the thyroid gland and pancreatic islets, while pituitary and adrenal gland often remained unstained. Although the expression of cytokeratins was found to be almost homogeneous in each glandular cell type, a certain variability was observed, depending on the organ examined and the treatment carried out.     

两种兔尾鼠的化学信息及其在群体中的作用

黄兔尾鼠(Lagurus lutens)及草原兔尾鼠(Lagurus lagurus)是新疆某些地区主要害鼠之一,它们的繁殖能力很强,数量高峰时,对草场危害极大。此外,它们还能传染某些地方性流行病,所以对这两种害鼠的防治是十分必要的。 近年来,我们在研究动物化学通讯的过程中,了解到外激素(信息素)在动物间传递信     

Adenosine deaminase complexing proteins are localized in exocrine glands of the rabbit

Adenosine deaminase complexing proteins have been localized in four exocrine glands of the rabbit by immunoperoxidase staining employing affinity-purified goat anti-rabbit complexing protein immunoglobulin as the primary antibody. In pancreatic acinar cells and in serous cells of Brunner glands (duodenal glands), staining was concentrated in granular appearing deposits between the nucleus and cell apex. Bile canaliculi, components of the exocrine liver, were also positive for complexing protein. In submaxillary glands, staining was localized in serous demilunes and striated ducts. In each instance staining was blocked by preincubating the primary antibody with complexing protein purified from rabbit kidney.     

Proteomic diagnosis of Sjögren's syndrome

In the last few years, a growing interest has arisen in the application of proteomic analysis to rheumatic disease. Sj?gren's syndrome is a systemic disease that affects exocrine glands directly, and is therefore expected to influence the composition of the whole human saliva and lachrymal fluid. Therefore, a rising number of studies have been performed in an attempt to characterize the salivary and lachrymal protein profiles of patients with Sj?gren's syndrome by using a proteomic approach. This review summarizes the state of the art and the potential application of proteomics in the systematic search for diagnostic biomarkers in Sj?gren's syndrome.     

Deficiency of α-mannosidase in Angus cattle. An inherited lysosomal storage disease

A disease of Angus cattle previously known as pseudolipidosis has been shown to be an inherited lysosomal storage disease, in which an oligosaccharide containing mannose and glucosamine is the storage substance. Diseased animals have a near-absolute deficiency of the lysosomal enzyme, alpha-mannosidase, whereas heterozygotes have a partial deficiency of this enzyme. The condition is analogous to the human disease known as mannosidosis.     

Occurrence and structural organization of the exocrine glands in the legs of ants

Apart from their obvious locomotory function and hence the presence of muscle fibres, ant legs are also endowed with an astonishing variety of exocrine glands. This paper reviews the presence and structural variety of the 20 different glands that have so far been found in the legs of ants. Four of these glands are described for the first time in this paper. Glands have been described in the three leg pairs, although considerable differences may exist. Glands occur in the various leg segments. A number of glands, especially those located in the hindlegs, may have a function in the production of trail pheromones. Other possible functions that have been reported deal with antenna cleaning, production of lubricant substances and sex pheromones.     

Reserpine treatment increases viscosity of fluid in the epididymis of rats

Reserpine treatment in rats induces morphological and functional disturbances in exocrine glands which resemble those produced by cystic fibrosis. The general feature is a decrease in fluid secretion with a rise in mucous concentration and altered electrolyte composition. Chronically reserpinized rats have therefore been used as an animal model for the disease. It is known that cystic fibrosis men are infertile due to obstruction of the epididymal duct with inspissated material, a phenomenon that may be secondary to abnormal electrolyte and water transport in the epididymis. Male rats were treated with reserpine (0.5 mg/kg/day) for 12 to 14 days. At the end of the treatment, epididymal fluids were flushed out from the cauda epididymidis for measurement of spermatocrit, viscosity, total protein concentration, sperm concentration and motility. It was found that reserpine treatment caused a rise in viscosity (by 40%), spermatocrit, sperm concentration, and protein concentration. These changes were observed in the epididymis of rats that had been efferent duct-ligated before reserpine treatment. Despite a rise in viscosity of the fluid bathing the spermatozoa, the viability of the stored spermatozoa was apparently normal. Spermatozoa were able to initiate forward motility when suspended in a sodium-containing medium. Testis fluid secretion measured by weight gain after efferent duct ligation for 16 h was not affected by reserpine treatment. The change in viscosity probably was due to a decrease in fluidity in the epididymis. It is concluded that reserpine treatment in rats produced changes in the exocrine functions of the epididymis similar to those seen in other exocrine glands.     

Ca-dependent K channels in exocrine salivary glands

In the last 15 years, remarkable progress has been realized in identifying the genes that encode the ion-transporting proteins involved in exocrine gland function, including salivary glands. Among these proteins, Ca²⁺-dependent K⁺ channels take part in key functions including membrane potential regulation, fluid movement and K⁺ secretion in exocrine glands. Two K⁺ channels have been identified in exocrine salivary glands: (1) a Ca²⁺-activated K⁺ channel of intermediate single channel conductance encoded by the KCNN4 gene, and (2) a voltage- and Ca²⁺-dependent K⁺ channel of large single channel conductance encoded by the KCNMA1 gene. This review focuses on the physiological roles of Ca²⁺-dependent K⁺ channels in exocrine salivary glands. We also discuss interesting recent findings on the regulation of Ca²⁺-dependent K⁺ channels by protein–protein interactions that may significantly impact exocrine gland physiology.     

Mitochondrial calcium in the life and death of exocrine secretory cells

The remarkable recent discoveries of the proteins mediating mitochondrial Ca(2+) transport (reviewed in this issue) provide an exciting opportunity to utilise this new knowledge to improve our fundamental understanding of relationships between Ca(2+) signalling and bioenergetics and, importantly, to improve the understanding of diseases in which Ca(2+) toxicity and mitochondrial malfunction play a crucial role. Ca(2+) is an important activator of exocrine secretion, a regulator of the bioenergetics of exocrine cells and a contributor to exocrine cell damage. Exocrine secretory cells, exocrine tissues and diseases affecting exocrine glands (like Sj?gren's syndrome and acute pancreatitis) will, therefore, provide worthy research areas for the application of this new knowledge of the Ca(2+) transport mechanisms in mitochondria.     

The fine structure of the pancreatic nerves of the domestic fowl

Summary The fine structure of the pancreatic nerves of the domestic fowl has been studied. Naked axon beadings were found in membranous contact with endocrine as well as exocrine cells. From an anatomical point of view it seems reasonable to suggest that the endocrine glands might be subjected to some influence of the autonomic nervous system.     

Exocrine secretion of epidermal growth factor from Brunner's glands. Stimulation by VIP and acetylcholine

Brunner's glands of the duodenum are innervated by cholinergic and VIP-ergic nerves, and the glands have been shown to contain epidermal growth factor (EGF). In this study the effect of VIP and acetylcholine (Ach) on secretion of EGF from Brunner's glands was investigated in the rat. Intravenous infusion of VIP stimulated the flow rate of duodenal secretion, an effect which was inhibited by atropine. Ach alone did not significantly increase flow rate, and combined infusion of VIP and Ach induced the same flow as VIP alone. Concentration of EGF in duodenal secretion was increased by infusion of Ach, and this effect was potentiated by VIP. Infusion of VIP alone did not influence EGF concentration. EGF output from Brunner's glands was significantly stimulated by i.v. infusion of VIP and of Ach and combined infusion further increased EGF output. The study has demonstrated exocrine secretion of EGF from Brunner's glands, and it is suggested that stimulation is mediated by interaction of neuronal VIP and Ach.     

First indication of gas embolism in a harbour porpoise (Phocoena phocoena) from German waters

In the last decade, a number of cetacean strandings have gas embolic pathology analogous to decompression sickness in man and experimental animals. Acute gas and fat embolic lesions have also been found in mass-stranded beaked whales causally linked to high-intensity anthropogenic mid-frequency sonar activities. Sporadic chronic gas embolic lesions have also been described. This communication describes a first case of numerous gas-filled fibrous cavities in the markedly enlarged liver of a dead adult male harbour porpoise stranded at the North Sea coast of Schleswig-Holstein, Germany. Additional pathological findings consisted of chronic parasitic granulomatous cholangiohepatitis, hepatic vein thrombosis, parasitic infestations of the bronchial tree and pulmonary blood vessels associated with bronchopneumonia and severe parasitic burden in both ear sinuses. The hepatic cavernous lesions are similar to those described in chronic gas bubble disease in other cetaceans, most likely resulting from decompression-related tissue supersaturation with nitrogen.     

The structure of the glands in the angulus oris of the Bank vole Clethrionomys glareolus

The presence of glands opening to the angulus oris region of the bank vole Clethrionomys glareolus has been confirmed. The glands are similar in general to the apocrine sweat glands of man and other animals although histological differences were noted. Also there was a marked sex difference in the diameters of the lumens of the secretory tubules in this study (undertaken in the late autumn and early winter) The hairs into which the glands open are larger than other hairs in the region, and the surface pattern of the scales is inverted.     

The Functions of the Thymus

In rodents the thymus performs at least two functions. It is a major site of lymphopoiesis in the embryo and newborn, with the resulting lymphocytes migrating from the thymus to seed the spleen, lymph nodes and other lymphoid organs. In addition, the thymus produces a hormone which has an immunotrophic effect, i.e. it endows cells having immunological potential with immunological competence. In some animals other organs, in addition to the thymus, are responsible for directing the normal development of the immunological system. These are the bursa of Fabricius in birds and the appendix in rabbits. In humans it has been postulated that the tonsillar tissues may play an analogous role. Animal experiments involving extirpation of the immunotrophic lymphoid tissues have led to a better understanding of immunological deficiency diseases in man.