EPITHELIUM

Maj Rishi PokhrelDept of anatomy

NAIHSwww.slideshare.net

Histology?

• Microscopic anatomy?

At the end of this class you should be able to ..

• Define epithelium• Classify epithelium with examples• Correlate epithelium with their function

INTRODUCTION

• Primary tissue• Epi - Upon, Thelia - Projection, Nipple

PAPILLA/ PROJECTION

DEFINITION: layer (s) of cells that covers body surfaces, lines body cavities or constitute glands

DEVELOPMENT

• From all three germ layers• Ectoderm - skin, mouth, nose, anal canal• Endoderm - GIT, glands, resp tract, distal parts

of GU tract• Mesoderm - body cavities, endothelium,

proximal parts of GU tract

CHIEF CHARACTERS

• Predominantly cellular• Adhesion• Basement membrane

» Basal lamina» Reticular lamina

• Avascular• Cell shape• Regeneration - tumors common

FUNCTIONS•Secretion- columnar epithelium of stomach and gastric gland

•Absorption- columnar epithelium in intestine and PCT in kidney

•Transportation- material of cells along the surface of epithelium by motile cilia

•Protection- skin and urothelium in bladder

•Receptor- taste and olfaction

•Lubrication

CLASSIFICATIONEPITHELIUM

UNILAMINAR(SIMPLE)

MULTILAMINAR(STRATIFIED)

SQUAMOUS

COLUMNAR

CUBOIDAL

STR SQUAMOUS

STR COLUMNAR

STR CUBOIDAL

TRANSITIONAL

PSEUDOSTRATIFIED

Specialization

Simple squamous epithelium•A single layer of flattened cell ( “pavement”) disc shaped central nuclei •Thin cytoplasm

SIMPLE CUBOIDAL EPITHELIUM

SIMPLE COLUMNAR EPITELIUM

COLUMNAR EPITHELIUM WITH MICROVILLI

Gall bladder

CILIATED COLOUMNAR EPITHELIUM

Brush border

CILIATED COLOUMNAR EPITHELIUM

GOBLET CELL

PSEUDOSTRATIFIED COLUMNAR NON-CILIATED

PSEUDOSTRATIFIED COLUMNAR CILIATED

PSEUDOSTRATIFIED COLUMNAR WITH STEREOCILIA

Epididymis

STR SQUAMOUS NON KER EPITHELIUM

STR SQUAMOUS KER EPITHELIUM

STR CUBOIDAL EPITHELIUM

STR CUBOIDAL EPITHELIUM

STRATIFIED COLUMNAR

TRANSITIONAL EPITHELIUM

TRANSITIONAL EPITHELIUM

Assignment

• Cell junctions??

?

CONTACTS BETWEEN ADJOINING CELLS

CLASSIFICATN OF CELL CONTACTS

1. UNSPECIALISED CONTACTS2. SPECIALISED JUNCTIONAL STRS

A. Occluding jns or Zonula occludens or tight jns

B. Anchoring jns or Adhesive jns• Adhesive belts or Zonula adherens• Adhesive strips or Fascia adherens• Adhesive spot (Desmosomes, Maculae

adherens)

C. Communicating jns or gap jns

INTERCELLULAR JUNCTIONS(JUNCTIONAL COMPLEXES)

ZONULA OCCLUDENS ZONULA

ADHERENS

DESMOSOME

HEMIDESMOSOME

GAP JUNCTION

UNSPECIALISED CONTACT

• Cell adhesion molecules• In intercellular gap• Glycoprotein & proteoglycan

ZONULA OCCLUDENS

•Apical part of cell•Band or belt•Sealing effect•Eg. Intestine, urinary bladder

DESMOSOME ZONULA ADHERENS

ANCHORING JUNCTIONS

GAP JUNCTION

•Lateral surface of epithelial cells•Numerous transmembrane protein channels•Permit inorganic ions, small molecules, nutrients, chem messengers

TEST