FIG. 3. TRANSITIONAL. EPITHELIUM OF BLADDER.
Magnified 300 times: a, superficial layer of cells; b, In termediate layer of cells; c, deep layer of cells; d, fibrous tissue.
lungs, the membranous labyrinth of the ear, and occurs in a few other places. It consists of a single layer of flat cells, presenting the appear ance of a mosaic when seen from the flat surface. (b) Stratified Srynamous Epithelium.—Here the cells arc laid clown in several layers, only the surface cells being fiat, the deeper lay ers irregular or cuboidal in shape, the in nermost layer resting on a distinct mem brane. the membrana propria. Sometimes the cells of the middle layers are united by minute spines and are known as prickle cells. The main location of this form of epithelium are the skill and all its openings — the (esophagus. larynx, pharynx, ureter, bladder, pelvis of the kidney, the entire female urethra, and the terminal por tion of the male urethra.
ComTIENAR EPITHELIUM. (a ) Simple.—
This consists of a single layer of columnar cells placed side by side, their bases resting on a thin membrane, the membrana propria or basement membrane. Epithelium of this type lines the entire alimentary tract, the duets of glands, and their alveoli and portions of the male urethra.
(1)) Ntratified ro/matiar Epithelium.—Only the surface cells are truly eolumnar, the deeper layers being made lip of eells irregular in shape. It is not widely distributed. examples being found in the ras deferens and in the nasal fossve.
Ill. MODIFIED KurritEllum. (a) Ciliated.— These cells have minute, hair-like projections from their free surfaces, known as cilia. These cilia possess a vibratory motion, always acting in the same direction, and thus determining flow of cur rents. They occur only on columnar epithelium, either of the simple or stratified type. Ciliated epithelium lines the cavity of the uterus, the ovi