Human vaginal epithelial multilayer tissue culture

Summary Fragments of normal human adult vagina, when explanted onto glass slides gave rise to outgrowing sheets of pure epithelium, which had microscopic morphological features in common with normal vaginal epithelium. Infrequent fibroblast contamination was observed. Proliferating epithelial cells formedmultilayers of stratified squamous epithelium and demonstrated a progressive decrease in proliferative activity after 14 days. Continuous lines of epithelial cells were not obtained. Even in the absence of estrogens, transmission electron microscopy revealed evidence of keratinization of the superficial cells of the multilayer. Scanning electron microscopy of the surface of mature epithelial cells in culture revealed ultrastructural features that closely resembled those present on the surface of exfoliated cells obtained by scraping the vagina in vivo. This in vitro tissue culture model of human vaginal epithelium may provide a simple method of studying factors that influence vaginal epithelium growth, maturation and function.     

Apoptosis and Desquamation of Urothelial Cells in Tissue Remodeling During Rat Postnatal Development

Postnatal rat urothelium was studied from day 0 to day 14, when intense cell loss as part of tissue remodeling was expected. The morphological and biochemical characteristics of urothelial cells in the tissue and released cells were investigated by light and electron microscopy, by terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling (TUNEL) assay, by annexin V/propidium iodide assay, and by immunofluorescent detection of active caspases and tight-junction protein occludin. Intense apoptosis and massive desquamation were detected between postnatal days 7 and 10. During this period, active caspases and TUNEL-positive cells were found in the urothelium. Disassembled cell–cell junctions were detected between cells. The majority of desquamated cells expressed no apoptotic cell morphology, but were active caspase positive and TUNEL positive. Ann+/PI− apoptotic bodies and desquamated Ann+/PI+ cells were detected in the lumen. These results indicate that apoptosis and desquamation participate in urothelial cell loss in the rat early postnatal period, indispensable for fast urothelial remodeling during development. (J Histochem Cytochem 57:721–730, 2009)     

Skin as a potential source of infectious foot and mouth disease aerosols

This review examines whether exfoliated, virus-infected animal skin cells could be an important source of infectious foot and mouth disease virus (FMDV) aerosols. Infectious material rafting on skin cell aerosols is an established means of transmitting other diseases. The evidence for a similar mechanism for FMDV is: (i) FMDV is trophic for animal skin and FMDV epidermis titres are high, even in macroscopically normal skin; (ii) estimates for FMDV skin cell aerosol emissions appear consistent with measured aerosol emission rates and are orders of magnitude larger than the minimum infectious dose; (iii) the timing of infectious FMDV aerosol emissions is consistent with the timing of high FMDV skin concentrations; (iv) measured FMDV aerosol sizes are consistent with skin cell aerosols; and (v) FMDV stability in natural aerosols is consistent with that expected for skin cell aerosols. While these findings support the hypothesis, this review is insufficient, in and of itself, to prove the hypothesis and specific follow-on experiments are proposed. If this hypothesis is validated, (i) new FMDV detection, management and decontamination approaches could be developed and (ii) the relevance of skin cells to the spread of viral disease may need to be reassessed as skin cells may protect viruses against otherwise adverse environmental conditions.     

THE DISTINCT STEPS OF CELL DETACHMENT DURING DEVELOPMENT OF MOUSE UROEPITHELIAL CELLS IN THE BLADDER

In developing mouse urinary bladder the urothelial cells respond to urine accumulation by cell detachment, i.e. desquamation. To elucidate the steps of urothelial cell detachment during embryonic development and first urine accumulation in bladder lumen, superficial and intermediate cell layers were investigated. Different electron microscopic and cytochemical methods have been used. It was possible to distinguish between an early and late events on the basis of morphology. At the beginning cell detachment involves interruption of tight junctions between neighbouring superficial cells and the formation of numerous endocytotic vesicles. Endocytotic and cup-shaped vesicles then fuse and form large parallel rows of vacuoles and multivesicular bodies in desquamating superficial cells and in the neighbouring superficial and intermediate cells. These observations clearly demonstrate the existence of specific steps during the detachment of embryonic uroepithelial cells. Apoptosis accompanies cell desquamation. Only predetermined superficial bridge cells die in an apoptotic manner.     

12-O-tetradecanoylphorbol-13-acetate induces selective desquamation of superficial cells in rat urinary bladder epithelium

Summary 12-O-tetradecanoylphorbol-13-acetate (TPA) is known to affect the proliferation and/or differentiation of several types of cells. We injected TPA directly into the lumen of rat bladder to determine, using scanning and transmission electron microscopy, its effects on the bladder epithelium in vivo. At 1 h after TPA injection (1g/ml), the superficial cells of the epithelium had changed their morphology, and large spherical vacuoles occupied their cytoplasm. In some areas, the underlying intermediate cells were exposed by the desquamation of the superficial cells. During the next few hours, TPA was excreted from the bladder lumen by voluntary micturition, but the desquamation of the superficial cells proceeded further. All the superficial cells were lost from the luminal surface by 24 h after TPA injection. The changes noted were specific for the superficial cells and were not observed in the intermediate or basal cells. After 24h, part of the epithelium had a three-layer structure, indicating that regeneration was taking place. These results demonstrate that TPA selectively affects and desquamates superficial cells in a short period of time. This experimental system may be useful for studying in vivo cell proliferation and/or differentiation.     

A comparative study of the desquamation of urothelial cells during gestation and in adults mice following moderate stress or endotoxin treatment

The present paper deals with the comparative EM study of the detachment of mouse urinary bladder epithelial cells under various physiological conditions, namely, during gestation and in adult mice following induction by endotoxin or by exposure to moderate stress. It has been shown that desquamation during gestation involves two distinct modes, shedding of single cells and formation of apoptotic bodies. Moderate stress in adult female mice induced by constant illumination for 72 or 96 hours, results in desquamation of superficial and intermediate cells. Application of LPS is followed by desquamation of single cells and whole sheets of cells. Cell detachment involves interruption of tight junctions between neighbouring cells and formation of numerous cup shaped vesicles, multivesicular bodies and vacuoles at the base of desquamating cells. LPS induces desquamation entails delivery of lysosomal enzymes extracellulary into the intercellular space. In the areas of sloughing the bladder epithelium lack permeability barrier. Desquamated cells in the bladder lumen are mostly alive. These results clearly demonstrate the existence of specific adhesion mechanisms of detachment and desquamation of uroepithelial cells.     

The response of junctional complexes to induced desquamation in mouse bladder urothelium

During desquamation, the cells of mouse urinary bladder epithelium undergo detachment. In this process we examined the disconnection of cell adhesion molecules. Two proteins of cell junctions were studied: ZO1 of tight junctions and desmoplakin of desmosomes. Desquamation was induced by intravesical injection of LPS, constant illumination of mouse for 96 h, application of a combination of stress hormones hydrocortisone and norepinephrine or by removal of calcium with EGTA. All the inducers caused penetration of lanthanum tracer through the tight junctions, indicating paracellular permeability. Dilatation of extracellular spaces between neighboring cells was seen whenever desquamation was induced in bladders containing urine. Desquamation of single cells as well as groups of cells was observed. Contrary to obvious disconnection of cell junctions, as a precondition for desquamation, the distribution of junctional proteins did not change either in urothelial tissue or in desquamated cells. This study demonstrates that all the inducers of desquamation cause first an extensive dysfunction of a blood urine barrier and after that an occasional mechanical disconnection of adhesive junctions which consequently leads to desquamation.     

Apoptosis and cell desquamation in repair process of ischemic tubular necrosis

To elucidate the role of apoptosis and cell desquamation in the repair phase of acute tubular necrosis, morphological findings after 60 min ischaemia were investigated in rats. A morphometric analysis of the cell proliferation and of the epithelial cellularity of reconstructing tubules was performed. The kinetics of apoptosis and cell desquamation were also examined. Ischaemia and reperfusion injury resulted in widespread necrosis of tubules at day 1. Subsequently, a regenerative epithelial hyperplasia took place in the aarly stage. The most marked increase in cellularlity in the damaged tubules was on day 6, when the tubules became lined by hyperplastic epithelial cells with papillary clusters. The number of papillary clusters decrease up to day 8, and during this period many desquamated cells from the clusters were observed in the tubular lumen. In the later stage, hyperplastic epithelial cells were reduced to their original cellularity and during this period the number of apoptotic cells obviously increased, while the damaged tubules were reconstructed. We conclude that epithelial over-production occurs in the early phase after tubular necrosis, and excess hyperplastic epithelial cells regress during the repair process by cell desquamation and apoptosis, both of which are essential for the recovery of the original tubular structure.