MS1 Epithelium

What are the 4 Basic Tissues?

1. Epithelium

2. Nerve

3. Connective

4. Muscle

Basic dye

• cation

  • Carries a positive charge

  • Reacts with anions of the tissue (phosphate groups of the nucleic acids, sulphate groups of GAGs, carboxyl groups of proteins)

• Basophilic

Basic specific dyes

• Hematoxylin (with mordants)

• Toluidine blue

• Methylene blue

• Basic fuchsin

• Carmine

Structures that are basophilic

Fewer structures are basophilic than acidophilic

• Heterochromatin and nucleoli

• Cytoplasm

• extracellular matrix

Acidic dye

• Anion

  • carries a negative charge and reacts with cations of the tissue

• Acidophilic

Acidic specific dyes

• •Eosin (Eosinophillic)

• •Orange G

• •Phloxine

• •Anilin blue

• •Light green

• •Mallory

  • ­Aniline blue – for collagen

  • ­Acid fuchsin – for cytoplasm

  • ­Orange G – red blood cells

Structures that are acidophilic

More structures are acidophilic than basophilic

• Cytoplasmic filaments

• Intracellular membranous components

• Extracellular fibers (Collagen)

Epithelium is composed of _______ and a ________ ________

1. cells

2. basement membrane

Epithelium is ______ and support depends on __________.

1. avascular

2. diffusion

Epithelium is renewed continuously though _________.

1. mitosis

Epithelium selective barriers

1. external surface – skin (protective layer)

2. “tubes” and cavities – mucosa/endothelium and mesothelium

Epithelium is absent from:

1. articular cartilage

2. anterior surface of iris

3. enamel of teeth

Functions of Epithelium

1. Protection & support (skin, meninges)

2. Absorption (intestines)

3. Filter stuff (kidneys, lymphatics)

4. Transport & delivery

   1. nutrients (gut, blood vessels)

   2. waste (kidney, blood vessels)

   3. gases (airway)

5. Make stuff (secretions from glands)

   1. exocrine

   2. endocrine

6. Movements of organs

   1. mesothelia: pleura, pericardium, peritoneum

7. Sensory receptors for special senses:

   1. olfactory epithelium, hair cells, taste buds, rods/cones

Three main common features of epithelial cells

1. Closely apposed and linked (junctions)

2. Polarized

   1. free, apical domain

   2. lateral domain

   3. basal domain

3. Anchored to the basement membrane

Label!

1. basal domain

2. lateral domain

3. apical domain

Identify!

simple squamous

Identify!

simple cuboidal

Identify!

simple columnar

Identify!

Pseudostratified

Identify!

Stratified squamous

Identify!

Stratified cuboidal

Identify!

Stratified columnar

Identify!

Transitional

Identify!

Simple columnar

Identify!

Stratified columnae

Identify!

simple columnar

Identify!

Pseudostratified

Identify!

Stratified squamous

Identify!

Simple squamous

Identify!

Transitional

Identify!

Microvilli

Identify!

Stereocilia/Stereovilli

Identify!

Motile Cilia

• move in synchronous, undulating patterns

• move particles, oocytes through the tubes

• cilia are anchored to cytoskeleton via basal body

Identify!

Pseudostratified Epithelium

Identify!

Cochlear Hair Cells

Identify!

1. Gut microvilli

Lateral Domain Terminal Bar, Junctional Complex

1. Occluding/Tight junctions/zonula occludens

2. Anchoring junctions

3. Communicating junctions (gap junctions)

Occluding/Tight junctions/zonula occludens

• Linked to actin

• Separates cellular and tissue compartments

Three major transmembrane proteins of Occluding/Tight junctions/zonula occludens

• Occludin

• Claudins

• Junctional adhesion molecule (JAM)

Anchoring junctions

• Linked to actin and intermediate filaments

• Zonula adherens → actin

• Macula adherens (desmosome) → intermediate filaments

Lateral folds

folds of plasma membrane

increasing surface area

The Basal Domain

Involved in cell-to-matrix adhesion.

1. Basement membrane

2. Cell-to-ECM junctions

   1. Focal adhesions → actin

   2. Hemidesmosome → intermediate filaments

3. Basal cell membrane infoldings

Epithelial Secretory Mechanisms

1. exocrine glands

2. endocrine glands

exocrine glands

• unicellular or multicellular (glands)

• Release product on epithelium surface

Histological Types of Endocrine Glands

• Release product into blood

  • Cord and clump

  • Follicle

Cord and Clump

• most common

• cells are arranged in interconnecting cords and clumps between dilated blood capillaries

• store hormone intracellularly

Follicle

group of cells forms a vesicle enclosing a central cavity in which hormone is stored

Identify!

cord and clump

endocrine

Identify!

follicle

endocrine

Types of Multicellular Glands

1. simple tubular

2. simple coiled tubular

3. simple tubular branched

4. simple acinar/alveolar

5. branched tubular

6. branched acinar/alveolar

7. branched tubuloacinar

Identify!

simple tubular gland

Identify!

Simple coiled tubular gland

Identify!

Simple tubular branched gland

Identify!

Simple acinar/alveolar gland

Identify!

Branched tubular gland

Identify!

Branched acinar/alveolar gland

Identify!

Branched tubuloacinar gland

Identify!

• ducts

  • lumen

• mucous secreting (stain pale with H&E)

• serous secreting

• serous demilune

Identify!

simple tubular gland

Identify!

simple columnar