The role of lamina propria and epidermal growth factor (EGF) in development and differentiation of urothelial cells in the urinary bladder in vivo and in vitro is poorly understood. The purpose of this study was to determine the effect of lamina propria and EGF on growth, differentiation and epithelial morphology of urothelial cells in cultures of mouse urinary bladder. Urothelial tissue cultures were maintained on a Cyclopore membrane in serum-free medium for 10 days, and thereafter analysed by light and electronmicroscopy using morphological, immunohistochemical and immunocytochemical methods. We found out that exogenously added EGF has no affect either on cell proliferation or differentiation. Therefore, we distinguished only between cultures which were growing in presence or absence of lamina propria. Our results show that urothelial cells, which grow with lamina propria (culture type I), have better growth and are more differentiated than urothelial cells, which grow with lamina propria only for first four days (culture type II). Urothelial cells, which grow all 10 days without lamina propria, are nondifferentiated. Urothelial cells in cultures type I and II show terminal differentiation from the Cyclopore membrane towardthe surface. On the surface of the new multilayer epithelium are the most differentiated cells with apical membrane shaped in microvilli, ropy microridges, rounded microridges or scalloped microridges. Immunohistochemicaland immunocytochemical analysis of uroplakins ,show that cells with asymmetricaly thickened membrane shaped in scalloped microridges are terminally differentiated. This is the first description of the syntesis of uroplakins and their assembly in the asymmetricaly thickened membrane in urothelial cells in vitro. (Abstract truncated at 2000 characters).

Temporary displacement of the free gingival margin is vital for identificationof the finish line of the preparation in a die plaster model. This enables accurate modelling of the margins of fixed restorations, which inturn ensures a proper relationship between crowns and gingival tissue. Thereare several methods for enlarging of sulcular space before impression making in clinical practiceČ mechanical and chemo-mechanical free gingival displacement, electrosurgery and rotary gingival curettage. However, all the methods have more or less adverse effects on the gingiva. This study only examined the effects of the chemical agents that are most commonly used for the impregnation of cotton cords, i.e. aluminum chloride of two concentrations, aluminum sulfate and tetrahydrozoline. The purpose of the study was to determine which agent caused sufficient displacement of free gingiva suitable for impression making while exerting the least inflammatory response in the gingival tissue and the least notable changes at the cell level. The study examined the effects of chemical agents on fibroblasts and keratinocytes in cell cultures and on dogs in vivo. Standard methods of cell viability measurements, such as cell viability test, cell survival test and colorimetric MTT test, were used on V-79 fibroblasts. The study was supplemented by scanning and transmision electron microscopy on rat keratinocytes. This method enabled us to qualitatively evaluate the differences between the control group and those treated with two agents, i.e. the most, and the least aggressive ones. (Abstract truncated at 2000 characters).