Prof. Dr. Xiaoxun Xie2006.10

What is Histology ?a science which studies normal microstructures & relationship between these structures and functions.

What is Tissue ? cells with their ground substance acting together performing particular functions.

What is organ? organized by multiple tissues in particular ways.

What is system? formed by several organs with related functions.

Molecules

Organelles

Cells

Tissues

Organs

Systems

Relative proportion & arrangement of tissue types determine the organ’s structure & capabilities.

Microscopy: Light microscopy (LM)

Electron microscopy (EM)• Transmission electron microscope (TEM)• Scanning electron microscope (SEM)

Staining: H&E Histochemistry immunohistochemistry In situ hybridiztion …

Methodology in Histology

TEM

SEM

Heamatoxylin: Base dye; blue color; combine with the acidic components

Eosin: Acidic dye; Red color; combine with the basic components

• basophilic• acidophilic (eosinopilic)• neutrophilc

nucleolus

nucleus

H&E ------ Routine staining for LM

H&E Staining

Hematoxylin(Base dye)

Eosin(acid dye)

Stain ：NucleusRERRibosome…

* Basophilia

Stain:CytoplasmLysosomeMitochodriaCollagen F…

*Acidophilia

Epithelial Tissue Tissue

Two basic types– Covering epithelia

outer layer of the skin

inner surface of cavities and vessels;

ducts of the exocrine glands– Glandular epithelia

* main function for secretion

* make up most of the glands

Other types: sensory /germinal epithelia

Name Distribution

Covering Epi. Surface of body, luminal organs & cavity organs

Glandular Epi. Glands (secretion part)

Sensory Epi. Sensory organs

Myoepithelium Basal portion of the glands

Germinal Epi. Sexual glands

Type and distribution of epitheliumType and distribution of epithelium

- Protection;

- Absorption;

- Lubrication;

- Excretion and Secretion;

- Sensory reception;

- Reproduction.

Functions of epithelium

Free (apical) Surface

Basement Membrane

C.T.

Characteristics of Epithelia

* Highly cellular with little intercellular space

* Polarity

* Avasculation: no blood vessels

* Supported by underlying connective tissue

* High regeneration capacity

Free, basal and lateral surfaces of epi.cells display specific structural modifications

Polarity

Classification of coveringClassification of covering EpitheliaEpithelia

based on following features:

- Number of cell layer

one layer: simple epi.

several layers: stratified epi.

- Shape of cells on the apical surface

flat: squamous epi.,

square: cuboidal epi.,

rectangular: columnar epi.,

- Specializations of cell surfaces: cilia

exception: transitional epi..

Classification depends on layer

Simple layerSimple layer Stratified layerStratified layer

Classification depends on cilia

•one layer of flat cells with one flat nucleus

•found in: -alveoli of the lungs, -kidney glomeruli, -heart, blood and lymphatic vessels -ventral body cavities.

• thinnest of all - gas diffusion - filtration - exchange of waste & nutrients filtration

Simple squamous epithelium

Simple squamous epithelium

1. Nuclei (flat and parallel to the surface of the epithelium)

2. Face to lumen

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The entire circulatory system is lined by a S. S. Epi. that is called endothelium.

Mesothelium

The major body cavities ( peritoneal, pleural, pericardial) are lined by S. S. epi that is called mesothelium.

serosa ( 浆膜）( mesothelium + CT )

lining thoracic cavity & covering the lungs----------pleura （胸膜）

lining abdominal cavity & covering the abdominal organs -----peritoneum （腹膜）

enclosing the heart -----pericardium （心包膜）

- Cuboidal cells with one round nucleus

- surface view: six sides-hexagonal

- distribution:

small glands,

kidney tubules,

ovary surface, ect.

Simple Cuboidal Epithelium

Simple Cuboidal EpitheliumSimple Cuboidal Epithelium

columnar cells with one oval nucleus

• Two subtypes:

-non-ciliated:

*microvilli on its apical surface.

*found in digestive tract, ducts of some glands.

*function: absorption of digested food products; secretion of mucus, enzymes, ect.

- ciliated: * cilia on its apical surface.* found in uterine and uterine tubes.

Simple Columnar Epithelium

Pseudostratified ciliated columnar epithelium

Different types of cells

Columnar cell----------------------Goblet cell ---------------------------------------------

Fusiform cell------------------------

Basal cell--------------------------------

All cells rest on the BM

Not all can reach to the free surface

cilia in columnar cell

Differences between stratified & pseudostratified

• Appears layers but all cells touch the basement membrane

B.M.

Stratified Pseudostratified

1. Nuclei2. Epithelium3. Cilia 4. Lumen

Pseudostratified ciliated columnar epithelium

Stratified EpitheliumStratified Epithelium

Stratified squamous: the outer layer of skin

Stratified cuboidal and columnar: large ducts of glands

Transitional: lining of urinary organs can stretch as the bladder fills

Stratified Squamous Epithelium

* Multi-layer cells

* Squamous cells in outermost layers

* Large/polygonal cells in intermediate regions

* cells in deep: cuboidal / low columnar resting on the BM

* two types: -Non-keratinised (mucous)

-Keratinised (skin)

Keratinization: a process by which the superficial cells die and become tough, hard squama.

* to accommodate distension and stretching of organ.

* Lining of urinary bladder and ureter.

Transitional Epithelium

Specializations of Epithelial Cells

- Glycocalyx: glycoprotein containing coat

- Cilia

- Microvilli

- Stereocilia: very long microvilli (immotile)

Specializations in cellular apical surface

Cilia

• elongated, motile

structures;

• 0.3~0.5 µm (diameter);

• 5~10 µm long.

KARTEGENER’S SYNDROME

• Absence of dynein arms• Respiratory difficulty• Males sterile- flagellum of sperm is modified ciliu

m

Plasma Membrane

Microtubule Doublet

Dynein

Microvilli

• "brush border" ( LM)• Finger-like projection(EM)• 0.1 µm in diameter• 1 µm long

Brush border

MICROVILLI STRUCTURE

• covered by the cell membrane

• microfilaments in the core

• microfilaments interact

with terminal web

ZA

Microvilli

Cell membrane

visible network of horizontal actin filaments on the apical of an epithelial cell.

Microvilli Cilia

appearance Small and short Big & long

observation EM LM

Surface Cell-membrane Cell-membrane

Axes Cytoplasm Cytoplasm

Microfilament MicrotubuleBasal portion Terminal web Basal body

Function Increase surface area Movement

Difference between microvilli & cilia

Plasma membrane

Microvilli-with core filaments

Specializations in cellular lateral surface

* at the apical border of the cell;

* outer layers of plasma membrane fuse together;

* forming a waterproof belt

surrounding the cell;

* serving as a barrier;

* Preventing diffusion of

molecules between cells.

Tight junction (zonula occluden)

* located just below the tight j. as a 'belt'

* intercellular space (15-20 nm) with an adhering

substance (glycoprotein)

* microfilaments associated with

cytoplasmic surface of epi. cell

* Function in mechanical

attachment

Intermediate Junction (Zonula Adherens)

Tonofilaments--------------

Attachment plaque------

Desmosome (Macula Adherens)

• Spot-like

• intercellular space 25-30 nm with a intermediate line

• attachment plaques in cytoplasmic surface

• tonofilaments

intermediate line

Gap junction

Connexon-------------

* Narrow intercellular space spanned by connexon

* A low-resistance pathway between cells

* Not only in the epithelial cells.

Cell membrane

Gap / Communicating Junction

Gap Junction

3 or 4 junctions are collectively termed junctional complexes.

Pemphigus

Specialization of the cellular basal surface

• Hemi-desmosome

• Basal infolding

• Basement membrane

Basal infoldings show the increased surface area available for the ion and water transport.

Basement membrane

• Amorphous material on LM• Two layers on EM• Function as connection and semi permeable membrane

Hemidesmosome

Basal Lamina

Reticular lamina

Glandular Epithelium

• A type of epithelial tissue whose primary function is secretion, and is the prominent tissue forming glands.

A specialization of epithelial tissue to secrete substances. It may consist of a single cell (unicell) or a multicellular arrangement.

Classified into two types of gland:– endocrine - internal secretion: produce hormones– exocrine - external secretion : secrete into body

cavities or the body surface i.e. tears, sweat, saliva

General structure of exocrine gland

• Secretory unit (acius)- serous cell- mucous cell

•duct

“TYPICAL” EXOCRINE GLAND STRUCTURE

Secretory Portion

Duct

Surface Epithelium

WHAT IS CONNECTIVE TISSUE(C.T)?

a basic type of tissue which provides structural

& metabolic support for other tissues and organs.

WHERE IS CONNECTIVE TISSUE FROM?

All C.T develop from mesenchyme (embryonal connective tissue).

General characteristics of C.T.

• relatively small number of cells without polarity

• intercellular material is the dominant component

• enrichment of blood and lymphatic vessels

• same origination-----from mesenchyme

• Function as

connecting, supporting, nutrition, defense, repair.

Umbilical Cord, human - H&E

Components of Connective Tissues

• Cells

• intercellular material---dominant component

matrix--- amorphous ground substance

• polysaccharide-rich macromolecules

•Tissue fluids

• ions

fibers: extracellular filamentous structure

Classification of Connective Tissue

Connective tissue proper

• Loose connective tissue (L.C.T)

• Dense Connective Tissue (D.C.T.)

• Adipose tissue

• Reticular tissue

Special connective tissue

• Cartilage

• Bone

• Blood

Introduction of L.C.T• most common type of C.T;

• most widely distributed in the body;

• sponge-like;

• greater variety of cells and fiber than other C.T;• flexible but not very resistant to stretching;

• Function as

-binding other tissue to each other;

-nutrients providing;

-wounding healing and destruction foreign matter.

A stretched preparation of L.CT. The pink fibers of different thicknesses are collagenous (or white) fibers. The dark, thin, more tortuous fibers are elastic (or yellow) fibers. Most of the nuclei belong to fibroblasts.

Component of L.C.T.

Cells Fibers Ground substance

Fibroblast Collagen glycosaminoglycan (GAG)

Macrophage Elastic proteins

Plasma cell Reticular tissue fluid

Mast cell

Fat cells (adipocyte)

Undifferentiated cell

Wandering cell

Ground substance

• jelly-like substance ， no definite shape

• contains: * proteoglycan Protein + glycosaminoglycan (GAG)

chondroitin sulphatekaratin sulphatehyaluric acid

* glycoprotein

• function as* diffusion of nutrients & metabolic waste* physical barrier

FIBROBLAST

Origin: mesenchymal cells LM:

Appearance: long flat cell with filopodia

Nucleus: oval and pale with fine chromatin; conspicuous nucleoli;

Cytoplasm: nearly homogenous,

weakly basophilic

Fibroblast fibrocyteinacitve

older

Fibroblast & Fibrocyte

fibroblast ——

fibrocyte——————

EM: rich in RERs, free ribosomes,

well-developed Golgi apparatus

Function:

involving in the synthesis

and secretion of :

* Proteins related to production of collagenous, reticular, and elastic fibres.

* Ground substances

MACROPHAGE

Origin: monocytes

LM:

• irregular in shape

• blunt processes

(pseudopodia)

• acidophilic cytoplasm with

phagocytosing material

• inactive macrophages may look like fibroblasts

FIBROBLAST

Origin: mesenchymal cells LM:

Appearance: long flat cell with filopodia

Nucleus: oval and pale with fine chromatin; conspicuous nucleoli;

Cytoplasm: nearly homogenous,

weakly basophilic

Fibroblast fibrocyteinacitve

older

Fibroblast & Fibrocyte

fibroblast ——

fibrocyte——————

EM: rich in RERs, free ribosomes,

well-developed Golgi apparatus

Function:

involving in the synthesis

and secretion of :

* Proteins related to production of collagenous, reticular, and elastic fibres.

* Ground substances

MACROPHAGE

Origin: monocytes

LM:

• irregular in shape

• blunt processes

(pseudopodia)

• acidophilic cytoplasm with

phagocytosing material

• inactive macrophages may look like fibroblasts

EM* irregular surface with numerous finger-like projections* numerous lysosomes * many phagocytic vacuoles

Function of macrophages•phagocytosis and destruction of foreign bodies

•immune response

- capture, process and re-secrete antigen

- transfer antigen into lymphocytes

- stimulate immune response

•secrete bioactive products

lysosome emzyme

chemotatic factors for neutrophils

growth factors…

PLASMA CELL

Origin: B lymphocytesLM:

Appearance: round or ovoid

Cytoplasm: always basophilia ( ribosomal RNA)

pale stained perinuclear region

Nucleus: located eccentrically

clock-face chromatin arrangement

or wood-cart-wheel nucleus

FIBROBLAST

Origin: mesenchymal cells LM:

Appearance: long flat cell with filopodia

Nucleus: oval and pale with fine chromatin; conspicuous nucleoli;

Cytoplasm: nearly homogenous,

weakly basophilic

Fibroblast fibrocyteinacitve

older

Fibroblast & Fibrocyte

fibroblast ——

fibrocyte——————

EM: rich in RERs, free ribosomes,

well-developed Golgi apparatus

Function:

involving in the synthesis

and secretion of :

* Proteins related to production of collagenous, reticular, and elastic fibres.

* Ground substances

MACROPHAGE

Origin: monocytes

LM:

• irregular in shape

• blunt processes

(pseudopodia)

• acidophilic cytoplasm with

phagocytosing material

• inactive macrophages may look like fibroblasts

MAST CELLS

LM:Appearance: fairly large,

round, ovoid.Nucleus: non-lobulated spherical,

pale staining.Cytoplasm:

many coarse granules stains with basic dyes but exhibit metachromasia.

Phennomenon in which a basic dye changes color from blue to red/purple due to the dense presence of polyanionic groups (i.e. phosphates sulfates)

EM

• undulant surface folds • many secretion granules (very heterogeneous) containing:

*histamine

*heparin

*SRS-A

*other chemical

mediators

Function of mast cells

Involving in allergic reaction Antigen (Ag) IgE produced by plasma cell

binding to mast cells re-exposed to same Agre-exposed to same Ag

interacting with mast cell surface-bound IgE triggering triggering

Mast cell degranulation affecting various tissues/organsaffecting various tissues/organs

• increasing vascular permeability, edema• smooth muscle contraction

FAT CELLS ( ADIPOCYTES )

• cytoplasm is filled with lipid droplets

• a typical thin rim cytoplasm

• flattened nucleus is eccentric.