HISTOLOGY
EPITHELIUM CELLS
Stem Cells
• Early cells that are not programmed yet
• As development of the organism occurs, these stem cells become specialized.
• RISK: If function of the body rely on specialized cells, if those cells are destroyed or disabled, it could lead to disaster for the organism
Primary Tissue
• Tissue: Cells with the same function and structure.
• There are four primary tissues:– Epithelium– Connective– Nervous– Muscle
EPITHELIAL TISSUE
• Specialized Characteristics– Fit closely together to form sheets
• Lots of tight junctions
– One surface exposed to body’s exterior or cavity– Basement Membrane
• Foundation for new cells
– Avascular• No blood supply of their own• Depend on Diffusion (Capillaries)
– Regenerate Easily
Epithelium Classification
Simple Squamous Epithelium• “Floor Tiles” Filtration, Diffusion
• Serous membranes, O2 and CO2 Diffusion, Capillaries
Simple Squamous Epithelium
Simple Cuboidal Epithelium• Glands, Ducts, Salivary Glands • One layer of cuboidal cells resting on a basement membrane
SIMPLE CUBOIDAL Epithelium
Simple Cuboidal Epithelium
Simple Columnar EpitheliumGoblet cells produce a lubricating mucus. Digestive Tract, Mucous membranes.
Simple Ciliated Columnar Epithelium
Pseudostratified Ciliated Epithethium
• Respiratory Tract; nuclei appear at different heights
Stratified Squamous Epithelium• Abuse/Friction, esophagus, mouth, outer skin
Stratified Squamous Epithelium
Stratified Squamous Epithelium
Stratified Cuboidal Epithelium• Usually found with 2 layers being cuboidal• Ducts of glands
Stratified Cuboidal Epithelium
Stratified Cuboidal Epithelium
Stratified Columnar EpitheliumDucts of large glands, basal cells vary in size. RARE
Transitional Epithelium• Highly modified, urinary bladder, ureters,
Transitional Epithelium