Department of Histology and Embryology The epithelial Tissue Department of Histology and Embryology

Epithelial Tissues • Classification of Epithelia ①Cell Shape

• Classification of Epithelia ①Cell Shapes ②Cell Layer Simple Stratified

Contents: Requirement: 1. Simple squamous epi. ( NO: 25) 2. Simple cuboidal epi( NO: 35) 3. Simple columnar epi. (NO: 1) 4. Pseudostratified ciliated columnar epi. (NO: 3) 5. Stratified squamous epi.( NO: 2) 6. Transitional epithelium ( NO: 33) Requirement: Master and recognize the main types of covering epithelia.

1.Simple squamous epithelium( surface view) Showpiece: Mesothelium Material: frog mesentery Method: silver nitrate stain( Spread slide)

surface view cell Irregular polygons Membrane and extrocellular substance Nuclei are not stained, appears oval or rounded shape The light brown granular cytoplasm Mesothelium

Vascular endothelium

Simple squamous epithelium( lateral view ) Slide NO. 25 Material: Stomach---- Mesothelium Method: H&E

Cells are flat shaped oblate nuclei

2.Simple cuboidal epithelium Slide NO. 35 Material: thyroid gland Method: H&E

Low power: Follicle: many big and small follicles. The wall is consisted of simple cuboidal epi. Colliod

High power: The cytoplasm is stained red. The cell is of square with a central round nucleus stained in purple blue. The cytoplasm is stained red. Note that the cells are as tall as they are wide

3. simple columnar epithelium Slide NO. 1 Material: human intestine Method: H&E

Low power： The outline of the villi is a line of the simple columnar epithelium 1

High power ： The outline of the villi is a line of the columnar cells. The oval nucleus is close to the base of the cell, stained in blue . The cytoplasm is stained in red. Striated bonder Goblet cells

Simple columnal epi.

4. pseudostratified ciliated columnar epi. Slide NO. 3 Material: Human trachea Method: H&E

Low power： The inner surface of the wall is a line of the pseudostratified ciliated columnar epi.

High power： 1.Cilia 2.Columnar cell cilia 3. Goblet cell. 4. Spindle cell 5.cone cell 6.Basement membrane cilia Basement membrane

Pseudostratified ciliated columnar epithelium 1 2 3 4

5. Stratified squamous epithelium Slide NO. 2 Material: human esophagus Method: H&E

Low power: The epi. is thick which lines the inner surface of the organ. It consists of many cell layers. 1. stratified squamous epithelium 1

High power: surface 1 intermediate 2 3 basal 1.squamous cell 2.polygonal cell 3.basal cell surface 1 intermediate 2 3 basal

Transitional epithelium Slide NO. 33 Material: Human urinary bladder Method: H&E

1 1.epithelium Low magnification: The epithelium consists of many cell layers . 1.epithelium 1 1

Middle Magnification : Think of which functional condition does this specimen belong to ? domeshaped cells. 2 Surface cells Middle cells layer Deep cells layer

The drawing Striated border Nucleolus Cell Cytoplasm Goblet cell simple columnar epithelium H&E stain 400 ×

QUESTIONS What are the general features of epithelial tissue? 1) contain more cells and less extracellular ground substance 2) Polarisaton: ---free outer surface: face the surface of the body or the lumen of an organ or gland ---basal surface: face underlying connective tissue 3)  Avascularity, but innervation: ---no blood vessels ---rich in nerve terminals 4) Having functions of protection, secretion, absorption and sensory reception