Accurnulation of keratinized cells within the infundibulum of pilosebaceous canal is important in the pathogenesis of acne. Light and electron microscopic study of experimentally induced comedones, from the rabbit's external ear canal, was performed to define the earIy morphologic changes within and around the epithelial lining of the comedones. In light microscopic observation, early comedone was composed of loose cohesive horny cells and late comedone was composed of a mixture of loose and tight cohcsive horny cells. Cohesion between horny cells occured, in eIectron microscopic study, in two different ways: initially, by the persistence of desmosomes; later, and to a lesser extent, by tight junctions, which tightly bound the horny cells together. Multiple lipid droplets within the horny ceIls and a gradual decrease in the numbrane coating granules were observed.
Acne Vulgaris ; Desmosomes ; Ear Canal ; Tight Junctions

No abstract available.
Gastroesophageal Reflux* ; Humans ; Intercellular Junctions* ; Tight Junction Proteins*

Tight junctions (TJs) are widely expressed in the most apical portion of both epithelial and endothelial cell-cell interactions, serving as a structural and functional basis for material transport through the paracellular pathway. TJs are multi-protein complex composed of transmembrane and cytoplasmic proteins. TJs constitute pores allowing materials with specific size and electrical charge to pass through the paracellular pathway, which is so called "barrier" function. Besides, TJs also separate the lumen and interstitial space of epithelium and endothelium by the function of "fence". Recently, there is increasing body of evidence regarding the crucial role of TJs, together with the possible signaling pathways, in many epithelial cells, such as salivary, airway, intestinal and renal epithelial cells. The present review focuses on the latest research progresses on TJs, including TJ's composing, structure, and function measurement, as well as the mechanisms for modulating TJ's functions in some important epithelial cell types. We hope that the review may provide new insight into the therapeutic strategy of epithelium-related disease by targeting TJs.
Cell Communication ; Epithelial Cells ; Epithelium ; Intestines ; Tight Junctions

Endothelial tight junctions (TJs) serve as an important barrier in vascular endothelial structure and maintain vascular function homeostasis. Occludin, the most representative tight junction protein, is involved in sealing cell connections and maintaining the integrity and permeability of vascular endothelium. Recent studies have shown that alterations in the expression, distribution, and structure of endothelial TJs may lead to many related vascular diseases and pathologies (such as stroke, atherosclerosis, and pulmonary hypertension etc.). Here, we reviewed the research advances on the relationship between occludin and vascular endothelial injury, including the biological information of occludin, the signal pathways that occludin exerts the protective effect of vascular endothelium, and the relationship between occludin and vascular endothelial injury-related diseases.
Endothelium, Vascular ; Occludin/genetics* ; Signal Transduction ; Tight Junctions

Claudin proteins are the most crucial components of tight junctions, and play an essential role in maintaining cell polarity, regulating cell permeability and the intercellular ion. In recent years, many studies have shown that abnormality of claudins expression is implicated in the tumor progression. The expression correlates with tumor prognosis and can serve as a biomarker of prognosis and potential therapeutic targets. This review summarizes the current knowledge regarding claudin dysregulation in cancer and highlights the progress in claudin-based treatments.
Claudins ; therapeutic use ; Enterotoxins ; Humans ; Neoplasms ; drug therapy ; Tight Junctions

The vascular endothelium is a dynamic structure responsible for the separation and regulated movement of biological material between circulation and interstitial fluid. Hormones and nutrients can move across the endothelium either via a transcellular or paracellular route. Transcellular endothelial transport is well understood and broadly acknowledged to play an important role in the normal and abnormal physiology of endothelial function. However, less is known about the role of the paracellular route. Although the concept of endothelial dysfunction in diabetes is now widely accepted, we suggest that alterations in paracellular transport should be studied in greater detail and incorporated into this model. In this review we provide an overview of endothelial paracellular permeability and discuss its potential importance in contributing to the development of diabetes and associated complications. Accordingly, we also contend that if better understood, altered endothelial paracellular permeability could be considered as a potential therapeutic target for diabetes.
Adherens Junctions ; Adiponectin ; Endothelium ; Endothelium, Vascular ; Extracellular Fluid ; Insulin ; Permeability ; Physiology ; Tight Junctions

OBJECTIVE: To study the effects of respiratory syncytial virus (RSV) infection on epidermal growth factor receptor (EGFR), tight junction association proteins and mucin in the human airway epithelial cells. METHODS: Human airway epithelial cells NCI-H292 were randomly treated by ultraviolet light-inactivated RSV (control group) or thawed RSV (RSV infection group). After 48 hours of treatment, the protein levels of occludin, E-cadherin, phosphorylated EGFR and EGFR in NCI-H292 cells were measured by Western blot. The distribution and expression levels of occludin and E-cadherin in NCI-H292 cells were examined by immunofluorescence technique. The expression levels of MUC5AC mRNA in NCI-H292 cells were assessed by RT-PCR. RESULTS: The protein levels of occludin and E-cadherin were significantly reduced in the RSV infection group compared with the control group (P<0.05). The protein levels of phosphorylated EGFR and EGFR increased significantly in the RSV infection group compared with the control group (P<0.05). The MUC5AC mRNA levels also increased significantly in the RSV infection group compared with the control group (P<0.05). CONCLUSIONS RSV may down-regulate the tight junction association proteins and up-regulate the expression of MUC5AC in airway epithelial cells, which contributes to epithelial barrier dysfunction. EGFR phosphorylation may play an important role in regulation of airway barrier.
Cell Line ; Epithelial Cells ; ErbB Receptors ; Humans ; Mucin 5AC ; Respiratory Syncytial Virus Infections ; Tight Junction Proteins ; Tight Junctions

BACKGROUND/AIMS: Detailed characterization of the ultrastructural morphology of intercellular space in gastroesophageal reflux disease has not been fully studied. We aimed to investigate whether subtle alteration in intercellular space structure and tight junction proteins might differ among patients with gastroesophageal reflux disease. METHODS: Esophageal biopsies at 5 cm above the gastroesophageal junction were obtained from 6 asymptomatic controls, 10 patients with reflux symptoms but without erosions, and 18 patients with erosions. The biopsies were morphologically evaluated by transmission electron microscopy, and by using immunohistochemistry for tight junction proteins (claudin-1 and claudin-2 proteins). RESULTS: The expressions of tight junction proteins did not differ between asymptomatic controls and gastroesophageal reflux disease patients. In patients with gastroesophageal reflux disease, altered desmosomal junction morphology was only found in upper stratified squamous epithelium. Dilated intercellular space occurred only in upper stratified squamous epithelium and in patients with erosive esophagitis. CONCLUSIONS: This study suggests that dilated intercellular space may not be uniformly present inside the esophageal mucosa and predominantly it is located in upper squamous epithelium. Presence of desmosomal junction alterations is associated with increased severity of gastroesophageal reflux disease. Besides dilated intercellular space, subtle changes in ultrastructural morphology of intercellular space allow better identification of inflamed esophageal mucosa relevant to acid reflux.
Biopsy ; Claudin-2 ; Epithelium ; Esophagogastric Junction ; Esophagus ; Extracellular Space ; Gastroesophageal Reflux ; Humans ; Immunohistochemistry ; Intercellular Junctions ; Microscopy, Electron, Transmission ; Mucous Membrane ; Tight Junction Proteins ; Tight Junctions

The gut epithelial barrier, which is composed of the mucosal layer and the intestinal epithelium, has multiple defense mechanisms and interconnected regulatory mechanisms against enteric microbial pathogens. However, many bacterial pathogens have highly evolved infectious stratagems that manipulate mucin production, epithelial cell-cell junctions, cell death, and cell turnover to promote their replication and pathogenicity in the gut epithelial barrier. In this review, we focus on current knowledge about how bacterial pathogens regulate mucin levels to circumvent the epithelial mucus barrier and target cell-cell junctions to invade deeper tissues and increase their colonization. We also describe how bacterial pathogens manipulate various modes of epithelial cell death to facilitate bacterial dissemination and virulence effects. Finally, we discuss recent investigating how bacterial pathogens regulate epithelial cell turnover and intestinal stem cell populations to modulate intestinal epithelium homeostasis.
Colon ; Defense Mechanisms ; Epithelial Cells ; Homeostasis ; Intercellular Junctions ; Intestinal Mucosa ; Mucins ; Mucus ; Stem Cells ; Tight Junctions ; Virulence

Our current understanding of the ultrastructure of the retina has been gained using transmis sion electron microscopy (TEM) of thin sections. Scanning electron microscopy was proven to be a very valuable adjunct to TEM in retinal research. The present study describes the surface features of the retina. The complex shape of Muller cells varies in different layers of the retina. The Muller cell processes surround the cell bodies in the ganglion cell Iayer and form a part of the inner limiting membrane. The external limiting membrane consists of tight junctions between the beginning of the photo receptors and the Muller cells. The Muller cells extend beyond the external limiting membrane to embrace the photoreceptors. The course of the fibers of the outer plexiform layer is almost parallel to the surface of the macula. The interphotoreceptor space has a reticular structure.
Ependymoglial Cells ; Ganglion Cysts ; Humans* ; Membranes ; Microscopy, Electron ; Microscopy, Electron, Scanning* ; Retina* ; Retinaldehyde ; Tight Junctions