ANATOMY&PHYSIOLOGY FOR NURSES

COMPOUND EPITHELIUM.  Consists of more than one layer of cells. Stratified Epithelium forms the epidermal layers of the skin.  It also lines the mouth, pharynx, oesophagus, the lower part of the urethra, the anal canal and the vagina, and covers the surface of the cornea. In these areas it does not become cornified. The outer layers of cells near the surface comprise the horny layer of the skin; these cells are flatterned and resemble scales.  The deepest layer of cells are columnar in shape.  These form the germinative layer and here the cells multiply by karyokinesis, pushing those above them nearer the surface until the superficial ones are cast off.  The cells between the basal layer and the horny zone are called 'prickly cells' they are connected to each other by fine tendrils which give them a prickly appearance when examined under the microscope. Transitional Epithelium is a compound stratified epithelium consisting of several layers of cells. It lines the urinary bladder, the pelvis of the kidney, the ureters and the upper part of the urethra. The deeper layers of cells in traditional epithelium are of the columnar type of cell with rounded ends which make them pyriform or pear-shaped. As the cells in the deeper layers multiply by dividing, the superficial layers of cells are cast off. The superficial cell layers in transitional epithelium are less scale- like than those of stratified epithelium.