The role of glycine as an inhibitory neurotransmitter is well established, and glycinergic neurons appear to play an important role in the mammalian retinae[Ikeda & Sheardown, 1983 ; Bolz et al., 1985]. Though it has been reported that certain conventional and displaced amacrine cells and a few of bipolar cells are consistently labeled with anti-glycine antiserum in the mammalian retinae so far[W ssle et al., 1986 ; Pourcho & Goebel, 1987 ; Davanger et al., 1991 ; Yoo & Chung, 1992], little has been studied on the synaptic circuitry of glycinergic neurons to clarify mechanism of its action in the visual processing of the mammalian retinae. This study was conducted to localize glycinergic neurons and to define their synaptic circuitry in the rat retina by immunocytochemical method using anti -glycine antiserum. The results were as follows : 1. Glycinergic neurons of the rat retina were conventional and displaced amacrine cells, interstitial cells and bipolar cells. 2. Glycinergic amacrine cells could be subdivided into two types, that is, A II amacrine cells and other amacrine cells, according to their ultrastructures. Glycinergic A II amacrine and other amacrine cell processes comprised postsynaptic dyad at the ribbon synapse of rod bipolar axon terminals in the sublamina b of the inner plexiform layer of the retina. Glycinprgic A II amacrine cell processes made gap junctions with axon terminals of unlabeled invaginating cone bipolar cells in the sublamina b, and made chemical synapses onto axon terminals of unlabeled flat cone bipolar cells and onto dendrites of ganglion cells in the sublamina a of the inner plexiform layer. In the sublamina b of the inner plexiform layer, g1ycinergic amacrine cell processes were postsynaptic to axon terminals of unlabeled invaginating cone bipolar cells, and made chemical output synapses onto axon terminals of unlabeled invaginating cone bipolar and rod bipolar cells and onto the dendrites of ganglion cells. Such cases that pre- and post-synaptic processes of glycinergic amacrine cell processes were non- glycinergic amacrine cell processes were frequently observed throughout the inner plexiform layer. In some cases, glycinergic amacrine cell processes receiving synaptic inputs from other glycinergic amacrine cell process made synaptic outputs onto the non-glycinergic or glycinergic amacrine cell processes. 3. Glycinergic bipolar cells could be subdivided into invaginating and flat cone bipolar cells. Postsynaptic dyads of cone bipolar cells at the ribbon synapses were non-glycinergic amacrine and amacrine cell processes, glycinergic amacrine and amacrine cell processes, glycinergic amacrine and non-glycinergic amacrine cell processes, and dendrite and dendrite of ganglion cells. These results demonstrate that [1] glycinergic A II amacrine cell receiving synaptic input from rod bipolar cells inhibit flat cone bipolar cells and OFF ganglion cells via chemical synapse, and excite ON cone bipolar cells via electrical synapse ; thereby visual information in the darkness can be transmitted to ON ganglion cells via ON cone bipolar cells, and [2] glycine released from glycinergic neurons inhibits directly ON and OFF ganglion cells or indirectly ON and OFF ganglion cells via non-glycinergic amacrine or bipolar cells.
Amacrine Cells ; Animals ; Darkness ; Dendrites ; Electrical Synapses ; Ganglion Cysts ; Gap Junctions ; Glycine ; Neurons* ; Neurotransmitter Agents ; Presynaptic Terminals ; Rats* ; Retina* ; Synapses

The vertebrate neuromuscular junction (NMJ) is considered as a “tripartite synapse” consisting of a motor axon terminal, a muscle endplate, and terminal Schwann cells that envelope the motor axon terminal. The neuregulin 1 (NRG1)-ErbB2 signaling pathway plays an important role in the development of the NMJ. We previously showed that Grb2-associated binder 1 (Gab1), a scaffolding mediator of receptor tyrosine kinase signaling, is required for NRG1-induced peripheral nerve myelination. Here, we determined the role of Gab1 in the development of the NMJ using muscle-specific conditional Gab1 knockout mice. The mutant mice showed delayed postnatal maturation of the NMJ. Furthermore, the selective loss of the gab1 gene in terminal Schwann cells produced delayed synaptic elimination with abnormal morphology of the motor endplate, suggesting that Gab1 in both muscles and terminal Schwann cells is required for proper NMJ development. Gab1 in terminal Schwann cells appeared to regulate the number and process elongation of terminal Schwann cells during synaptic elimination. However, Gab2 knockout mice did not show any defects in the development of the NMJ. Considering the role of Gab1 in postnatal peripheral nerve myelination, our findings suggest that Gab1 is a pleiotropic and important component of NRG1 signals during postnatal development of the peripheral neuromuscular system.
Animals ; Mice ; Mice, Knockout ; Motor Endplate ; Muscle, Skeletal* ; Muscles ; Myelin Sheath ; Neuregulin-1 ; Neuromuscular Junction ; Peripheral Nerves ; Presynaptic Terminals ; Protein-Tyrosine Kinases ; Schwann Cells* ; Synapses* ; Vertebrates

For studies on the developmental stages of migrating erythroid cells and the development of sinusoid, transmission and scanning electron microscopic observations were undertaken on rat fetal liver in 13, 15, 17, 19, 21 days of gestation. The results obtained were as follows. 1. The hepatic sinusoidal endothelium were mainly non-fenestrated cell and fenestrated cell with diaphragm before 17 days of gestation, but fenestrated cells without diaphragm began to appear after 17 days of gestation. Two types of fenestrae were observed, free and clustered fenestrae, but both types were not involved in migration of erythroid cells. 2. Endothelial cell was continuous with neighboring cells by intercellular junctions between lateral cytoplasmic processes with zonula adherens, and between perinuclear cytoplasms with macula adherens. 3. After 13 days of gestation, Kupffer cells showed as matured cell morphology of irregular shape with long cytoplasmic processes into hepatic cord and perisinusoidal space. 4. Migrating erythroid cells in rat fetal liver sinusoid were mainly consisted of immature erythroblasts from proerythroblast to acidophilic erythroblast. The migration occurred through the migrating pores formed on the various sites of the endothelial cytoplasm into the hepatic sinusoidal lumen with no relation to the maturation stages of erythroblast and endothelial cell. In summary, the migration of erythroid cells in the sinusoid of rat fetal liver occurred through the invasion and migration pores transiently formed at various sites of endothelial cytoplasm, and migrating erythroid cells were mainly nucleated immature types.
Adherens Junctions ; Animals ; Cytoplasm ; Diaphragm ; Emigration and Immigration ; Endothelial Cells ; Endothelium ; Erythroblasts ; Erythroid Cells* ; Intercellular Junctions ; Kupffer Cells ; Liver* ; Pregnancy ; Rats*

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

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

The contractility of corporal smooth muscle plays a critical role in human penile erectile process. Understanding the initiation, maintenance and modulation of corporal smooth muscle tone is a prequisite to improve understanding, diagnosis and treatment of erectile dysfunction. Despite this fact, indentification of both the precise mechanistic basis by which various agents exert their effects on individual corporal smooth muscle cells, moreover, the process by which these signals are spread among the diverse array of parenchymal cells in the paired corporal, remain somewhat of a physiological enigma. Therefore, this article aims at: 1. to review current knowledge of the regulation of corporal smooth muscle tone at the cellular and molecular level; 2. to review various methods used in the study of gap junction channel.
Animals ; Connexins ; physiology ; Gap Junctions ; physiology ; Humans ; Intercellular Junctions ; physiology ; Male ; Muscle, Smooth ; physiology ; Penis ; cytology

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

Cellular cardiomyoplasty has recently emerged as a potential new treatment of ischemic heart disease. Combining cellular cardiomyoplasty with gene therapy using myogenic transcription factor might facilitate myocardial regeneration. In this study, we engineered H9c2, L6 using plasmid vector to overexpress the transcription factor MEF2c, Nkx2.5 involved in cardiomyogenesis. We investigated 1) formation of intercellular junction in mono-culture and co-culture with cardiomyocyte for functional and structural synchronous contraction after transplantation, 2) differentiation into cardiomyocyte, 3) resistance to hypoxic condition. Each cell overexpressing MEF2 and Nkx2.5 was generated by gene transfection and clonal selection. CO-culture was performed that each cell line added over cultured cardiomyocyte. H9c2-MEF2c and H9c2-Nkx2.5 became long, spindle shape like cardiomyocyte. Troponin T, cardiac specific marker, was found spot-like pattern in H9c2-Nkx2.5. However, co-culture with cardiomyocyte did not induce differentiation all kinds of cells into cardiomyocyte. Connexin43, which is gap junction marker was increased in H9c2-MEF2c, H9c2-Nkx2.5, L6-MEF2c and L6-Nkx2.5. Especially, co-culture with cardiomyocyte resulted in elevation of connexin43 levels more than monoculture. Ultrastructurally, formations of gap junction and desmosome were found apparently in L6-Nkx2.5. Long-standing, strong, regular and more frequent contraction were observed in cardiomyocyte co-cultured with H9c2-MEF2c, H9c2-Nkx2.5, L6-MEF2c, L6-Nkx2.5, respectively. Neverthless, any cell did not have active contraction itself, but passive movement except cardiomyocyte. H9c2-MEF2c, L6-MEF2c and L6-Nkx2.5 had resistance to hypoxia compared with other groups. These results suggested that co-culture and overexpressions of MEF2c and Nkx2.5 induced differentiation into cardiomyocyte and played an important role on intercellular junction formation and hypoxic resistance. This would be a promising source of cellular cardiomyoplasty. Therefore, much more research would be essential for clinical application of cellular cardiomyoplasty and this study would be a basic source for further study of MEF2c and Nkx2.5 in cellular cardiomyoplasty.
Animals ; Anoxia ; Cardiomyoplasty ; Cell Line ; Cell Transplantation ; Coculture Techniques* ; Connexin 43 ; Desmosomes ; Gap Junctions ; Genetic Therapy ; Intercellular Junctions ; Myoblasts ; Myoblasts, Cardiac* ; Myocardial Ischemia ; Myocytes, Cardiac* ; Plasmids ; Rats* ; Regeneration ; Transcription Factors ; Transfection ; Troponin T

The purpose of this study was to investigate the distribution of neuropeptide Y (NPY) in the cat spinal trigeminal subnucleus caudalis following pulpectomy of mandibular premolars and molar by means of an immunohistochemical and immunoelectron microscopic study. The animals were divided into normal and experimental group which were sacrificed at 14 days after pulpectomy. The results were as follows; 1. On the light microscopic observation of the spinal trigeminal subnucleus caudalis in normal group, NPY-immunoreactivity (IR) was weak within lamina I and lamina II outer. In pulpectomy group, NPY-IR was strong and appeared to extend into lamina I and lamina II inner at 14 days. 2. On the immunoelectron microscopic observation of the spinal trigeminal subnucleus caudalis in normal group, NPY-IR was revealed in axon terminals, dendrites, myelinated axons and unmyelinated axons. NPY-IR was associated with membrane structures within microtubules, synaptic vesicles, outer membrane of mitochondria and inner surface of the axolemma. In NPY-immunoreactive structure, there was a small amount of DAB precipita-tions. 3. On the immunoelectron microscopic observation of the spinal trigeminal subnucleus caudalis at 14 days in pulpectomy group, the number of NPY-immunoreactive axon terminals, dendrites, myelinated axons and unmyelinated axons was increased than normal group. DAB precipitations in NPY-immunoreactive structure was increased than normal group. Some NPY-immunoreactive axon terminal formed synaptic glomerulus and axoaxonic synapse. 4. The results indicate that NPY-IR was increased in the spinal trigeminal subnucleus caudalis after pulpectomy, and it is speculated that the increased NPY by injury of peripheral nerve may participate in the processing of nociception.
Animals ; Axons ; Bicuspid ; Cats* ; Dendrites ; Immunohistochemistry ; Membranes ; Microtubules ; Mitochondria ; Molar ; Myelin Sheath ; Neuropeptide Y* ; Neuropeptides* ; Nociception ; Peripheral Nerves ; Presynaptic Terminals ; Pulpectomy* ; Synapses ; Synaptic Vesicles

Cadmium (Cd) affects cell proliferation, differentiation, apoptosis and other cellular activities and can cause numerous molecular lesions that would be relevant to carcinogenesis. The mechanism of adverse effects of Cd has been poorly understood and, especially on the tight junction. Since there is rare information about the effect of Cd on tight junction protein, we here investigated whether Cd can alter the localization of the proteins. This study examined Cd effects on of tight junction (occludin, ZO-1, and ZO-2) using MDCK cell culture. The change of MDCK cell and tight junction was investigated after treatment of cadmium with phase contrast microscopy, TEER, cell viability, Transmission electron microscopy and confocal laser microscopy. After treatment of cadmium, transendothelial electrical resistance decreased with time and concentration dependent manner. AlamarBlue assay revealed that decreased cell viability also decreased with time and concentration dependent manner. The tight junction moved down between intercellular spaces with decreased density and the cellular thickness around cell junctions decreased with increasing concentration and exposure time of CdCl2. The MDCK cells eventually showed cell death with. Confocal laser microscopy revealed that immunofluorescent reaction of occludin, ZO-1 and ZO-2 decreased. Occludin, ZO-1 and ZO-2 were disrupted at tight junction. These data suggest that after treatment of Cd, increased permeability of MDCK cell monolayer increased. This might be accompanied with disruption of occludin, ZO-1 and ZO-2.
Apoptosis ; Cadmium Chloride ; Cadmium* ; Carcinogenesis ; Cell Death ; Cell Proliferation ; Cell Survival ; Electric Impedance ; Epithelial Cells* ; Extracellular Space ; Intercellular Junctions ; Madin Darby Canine Kidney Cells ; Microscopy, Confocal ; Microscopy, Electron, Transmission ; Microscopy, Phase-Contrast ; Occludin ; Permeability ; Tight Junctions*