Ultrastructural study of the mucosal layer of the adult albino rat ureter

ABSTRACT

The ureter is a dynamic organ rather than a simple conduit through which urine flows. The aim of the study was to explore the electron microscopic structure of the mucosa of the rat ureter in a trial for understanding the adaptive functional interactions between the urothelium and the different components found in the lamina propria. The mucosa of the ureter of 10 adult healthy male albino rats was studied under a transmission electron microscope. The rat ureter mucosa was formed of urothelium and lamina propria. The uroepithelium consisted of basal, intermediate, and apical umbrella cells. The cytoplasm of the basal cells contained few rounded vesicles with homogeneous content, bundles of microfilaments, and ribonucleoprotein particles. Besides basal cells, a few bundle cells were observed; these cells contained small dense bodies retained within large vacuoles. Desmosomal junctions interconnected the neighboring intermediate cells of the urothelium, and many rounded vesicles, mitochondria, and Golgi saccules appeared in their cytoplasm. The apical plasma membrane of the umbrella cells showed plaques and intervening hinge regions. Some rounded and many fusiform vesicles appeared within their cytoplasm. The lamina propria contained many capillaries in concavities formed by the basal layer of the urothelium; their lining endothelial cells were unusually thick. Many telocytes appeared in close contact and encircled the blood capillaries and groups of nerve fibers in the lamina propria. The telocytes were interconnected with each other and with other connective tissue cells by their telopodes. The lamina propria also revealed immune cells such as eosinophils and mast cells. Morphological analysis of the ureter mucosa is providing clues how epithelial cells sense different stimuli and transduce-in these stimuli into the underlying nervous, vascular, and active cellular elements in the lamina propria