ISEM09 http://www.emtech.jp./6thisem/
Effect of Exogenous Collagen on Re-epithelialization of Skin Wound in Rabbits
This study was performed to assess the effects of exogenous collagen gel for the re-epithelialization of partial thickness skin wound healing in rabbits. Adult male rabbits (New Zealand White Rabbit) 1.5 - 2 kg, were used for experimental animals. Skin wounds (1.5 x 2 cm length) were created bilaterally on the flank of 10 rabbits and then treated a periods of 9 days. Wounds on the experimental site were treated with exogenous collagen gel as well as fabric material gauze dressing. Control site wounds were covered with fabric material gauze dressing alone. Histological findings indicated that the epithelial migration of the experimental site of rabbits was far more rapid than that in the other control wound sites. Moreover, exogenous collagen gel provided a moist environment to keep wound clean, and facilitate keratinocyte proliferation. The wound dressed with exogenous collagen gel demonstrated a significant increase in the healing rate and re-epithelialization. J. Biomed. Lab. Sci. 7 (2001) 17-25.
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A Recent Trends in the Regulation of Biological Transport
Electron Microscopic Studies on Cellular Characteristics and Transport Systems in Tight Epithelia
This analysed the transport properties of bladder mucosa known as the typical system of "tight epithelia" by using TEM observation with both rapid freeze-fracture electron microscopy and thin-section method and mainly analysed the cellular characteristics of turtle bladder epithelial cells.The bladder epithelium, like other tight epithelia, consists of a heterogenous populaion of cells. The majority of the mucosal cells are the granular cells and may function primarily in the process of the mucosal cells are the granular cells and may function primarily in the process of active Na+ reabsorption in turtle bladder. The remaining two types of cells are rich in mitochondria and is believed to be responsible for a single major transport system, namely, H+transport by A-type of cell and urinary HCO3- secretion by B-type of cell. As viewed in freeze-fracture electron micrograph, the tight junctions form a continuous tight seal around the epithelial cells, thus restricting diffusion in tight epithelia. In addition, the apical surface membranes have a popilation of rod-shaped intramembranous particles (IMPs). It is believed that these IMPs probably represent the components of the proton pump. However, it is likely that these characteristics of the apical transporter remain to be clarified in tight epithelial cells.
Studies on Transport Mechanisms of Turtle Bladder
It has been shown in this and earlier investigation that the turtle bladder mucosa has three main cell types on their mucosal surface. They are the granular cells, a CA cells, and A CA cells. The three major transport mechanisms that occurs in the turtle bladder are sodium reabsorption, proton secretion, and bicarbonate secretion. In the present work the transport mechanisms by bladder epithelial cells of freshwater turtle, Pseudemys scripta, are summarized as follows. 1. The granular cells play an important role in sodium transport, while the a and β CA cells do not appear to play a determining role in sodium transport. 2. It appears that the active sodium transport in the granular cells occurs in twostep process, implying that first, sodium diffuses into the cells, followed by an energy- dependent efflux step, which is catalyzed by the ouabain -sensitive Na-K ATPase. 3. The a type of CA cells are responsible for the proton secretion using the proton pump on the apical plasma membrane, while the β type of CA cells are believed to be responsible for bicarbonate secretion. 4. When looked at under freeze-fracture electron microscopy, the apical plasma membrane of a cells have a characteristic population of rod~shaped intramembranous particles which are believed to be components of the proton pumps. Conversely, β type of CA cells show rod-shaped particles in their basolateral plasma membranes, which is consistent with the proton absorptive, bicarbonate secretory mechanism.
5. In the turtle bladder, the a and β type of cells are believed to be both responsible for proton transport, but in opposite directions
Mechanisms of proton secretion by carbonic anhydrase-containing cells in
ning cells in turtle bladder
This study was carried out to examine the transport mechanism by observing the properties of cellular memrnbrane having an a type of carbonic(CA) containing cells in turtle Urinary bladder. The urinary bladder consists of a heterogenous population of cells. As a result of fine observation with traditional thin section electron microscopy, the bladder epithelium has three different cell types on mucosal surface. They are a basal cell, a granular cell and a third type of CA rich cell. The CA rich cells are divided into two distinct smaller groups within them and called them a type and β type of CA cells. The a type of CA cells are responsible for the proton secretion using the proton pumps on the apical plasma membrane, the β type of CA cells secrete bicarbonate via an oppositely-directed proton pumps in their basolateral plasma membrane. After performing the freeze-fracture technique, it was shown that there were distributed a large number of intramembranous particles having a special structure on the apical membrane of a type of CA-rich cells in the process of their H' secretion. In turtle bladder a type of CA-rich cells, this particle was the only prominent structure in the apical membrane. These intramembrane rod-shaped particles probably represent the integral membrane components of the proton pump. This result may explain that carbonic anhvdrase within epithelial cell of urinarv bladder takes part in formation of H+ and bicarbonate, that active transport of H+ is done, and that the reabsorption of bicarbonate suggests transport mechanism containing H+ secretion. However, it seems that more studies are required for considering their regular transport pathway.
Transepithelial transport and dynamic changes on apical membrane area of turtle bladder
The present study was carried out to analyze the evidence of membrane recycling, and the regulation of cellular transport by dynamic changes in apical membrane area that functionally interacts with the number of cytoplasmic vesicles. Under scanning electron micrographs, turtle bladder mucosa contain three main type of cells; granular cells and carbonic anhydrase (CA)-rich cells, deviding into a and b type of epithelial cell. The granular cell is the majority cell type of the mucosa comprising 80% of the total cell number. The remaining 20% of the cells are characteristically rich in carbonic anhydrase. Uptake of HRP was detected in the most vacuoles or tubulovesicles in both type of CA-rich cells in the turtle bladder, indicating that the part of plasma membrane was internalized in the apical cytoplasmic vacuoles. It seems quite likely that CA-rich cells possess intracellular vesicles carrying proton pumps which are recycling back to the apical plasma membrane. In turtle bladder, the granular cells actively secrete large quantities of mucin and other proteins by an exocytotic mechanism in an apparently constitutive fashion. The possibility that bladder epithelial cells secrete mucin via a regulated secretory pathway has not been rigorously examined and much is still to be determined about these issues from this cell type.
Freeze -Substitution and Freeze-Fracture Studies
on Epithelial Transport of Toad Bladder
The cellular ultrastructure of the toad urinary bladder was examined by freeze-substitution and freeze-fracture electron microscopy. The urinary bladder was composed of four cell types. These cell types include the granular cell, basal cell, mitochondria-rich cell, and mucous -secreting or goblet cell. Some of the epithelial structure and the transport properties in each type of bladder cell from toad, Bufo marinus, are summarized as follows. 1. The granular cells, which provide the majority of the luminal surface area, are characterized by numerous secretory granules observed in the apical cytoplasm. The surface bordering the lumen of the bladder is characterized by only a few short microvillis, and appears to be covered by a glycoprotein-rich surface coat. 2. The mitochondria -rich cells are the second most commonly observed superficial cell type, and are characterized by large number of mitochondria. Mitochondria are distributed throughout the cell, and the apical cytoplasm is crowded with short tubulovesicles that have clear contents. The ratio of mitochondria -rich cell to granular cell is about 1: 5 in toad bladder. 3. The mucous-secreting or goblet cells are characterized by electron-lucent mucous granules in the cytoplasm. Rough-surfaced endoplasmic reticulum occupy the cytoplasm at the cell base and between the mucous droplets. Free ribosomes are abundant, but only a few mitochondria and lysosomes occur in the basal cytoplasm. 4. The bladder epithelial cells are polarized such that the transport processes that take place on the apical plasma membrane differ from the baso-lateral plasma membrane. The long intercellular channels are sealed from the lumen by tight junctions so that they block back-diffusion to the luminal side. The tight junctions that join the cells are leaky to water, and thought to be involved in osmotic water flow across the toad bladder. There are thus two pathways for epithelial transport, transcellular pathway through the cells, and paracellular pathway in between the epithelial cells. 5. The distribution of intramembranous particles of granular apical plasma membrane is altered in forskolin-stimulated toad bladder. The present result suggests the possibility that the aggregated intramembranous particles observed in the apical membrane of granular cells may underlie forskolin-induced changes in membrane permeability, and this alteration appears to be of transport functional significance. However, more investigation including electrophysiological observations is necessary to further substantiate the functional significance of these intramembranous particle aggregation.
