Types of Epithelia A pictorial essay histology Types of Epithelia A pictorial essay

Epithelial Terms Simple: one layer thick Stratified: more than one layer thick, obvious by linear arrangement of stained nuclei Pseudo-Stratified: looks like more than one layer thick, but is actually only one layer thick. Transitional: like a super pseudo-stratified layer it is used for epithelial tissue that expands and contracts many times (like bladders, etc.)

Epithelial cell types Squamous Cuboidal Columnar

Simple squamous epithelium Squamous epithelium has that “dinner plate” look (thin on edge, roundish from the top.

Simple Squamous Cont’d Locations lining of ventral body cavities lining of heart and blood vessels lining of portions of kidney tubules cornea of eye, and alveoli of lungs Functions reduce friction control permeability perform absorption and secretion functions

Stratified squamous epithelium Layers of Squamous cells on the apical side with layers of stem cells on the basal side.

Stratified squamous cont’d Location surface of skin lining of mouth, throat, esophagus, rectum, anus and vagina Function provide physical protection against abrasion, pathogens, and chemicals

Simple cuboidal epithelium Cells shaped like cubes, with very large nuclei

Simple cuboidal cont’d Location glands, ducts, portions of kidney tubules, thyroid gland Function Limited protection, secretion and/or absorption

Stratified cuboidal epithelium Same cells as simple, just several layers

Stratified cuboidal cont’d Location lining of some ducts (rare) Function protection secretion absorption

Simple columnar epithelium The cells are column shaped and generally have the nucleus in the lower half.

Simple columnar cont’d

Simple columnar cont’d Location lining of stomach, intestine, gallbladder, uterine tubes, collecting ducts of kidney Function protection secretion absorption

Pseudostratified columnar epithelium Columnar cells whose nuclei fool you into thinking they are stratified.

Pseudostratified columnar cont’d This one is ciliated and pseudostratified

Pesudostratified columnar cont’d Location trachea lining of nasal cavity, bronchi Function protection secretion mucous transport

Stratified columnar epithelium Stacked columnar cells

Stratified Columnar Cont’d

Stratified columnar Cont’d Location salavary gland duct small areas of pharynx, epiglottis, anus, mammary ducts, and urethra Function protection

Transitional epitheilum Look carefully at the cells, they appear different shapes and bunched up.

Transitional cont’d Location Function urinary bladder renal pelvis ureters Function permit expansion and recoil after stretching

Test yourself What type of epithelial tissue is this ?

The answer If you guessed: Ciliated Pseudostratified Columnar Epithelium You were RIGHT !, Congratulations

End of show The Attack of the Ancient Connective Tissue Stay tuned for our next exciting episode: The Attack of the Ancient Connective Tissue