histology em

Nucleus

Nuclear envelope

Nuclear pore guarded by nuclear pore

complex

Nucleolus

Peripheral chromatin

NUCLEUS • Nuclear envelope guarded by nuclear pore complex

• Nuclear envelope has :

• Outer nuclear layer continuous with rER & studded with ribosomes

• Inner nuclear layer attached to Lamin intermediate filaments which give attachment for peripheral chromatin

• Perinuclear space

• Nucleolus formed of 3 electron dense regions:

1. Pars fibrosa: containing rRNA strand

2. Pars granulosa: containing newly formed ribosomes

3. DNA organizer: less electron dense [pale stained]

• Function of nucleolus: formation of ribosomes.

• Condensed chromatin arranged in nucleus in 3 regions:

1. Peripheral chromatin

2. Nucleolus associated

3. Islands [granules] in the nuclear sap

Nuclear envelope & nucleolus disappear at late prophase of mitosis

Mitochondria

cristae

Dense bodies

Mitochondria

rER

Free ribosomes

Mitochondria

• Enzymes of phosphorylation are present on the cristae

• Mitochondrial matrix contain enzymes of Krebs cycle & fatty acid oxidation ,RNA,DNA & Ca

• Mitochondria with tubular cristae are present in steroid forming cells

• Mitochondria are stained for LM by iron Hx & silver

• Function: ATP formation, thermogenesis in brown fat, fatty acid oxidation, help in ca regulation, help in steroidogenesis in steroid forming cells

Golgi Apparatus

http://www.cytochemistry.net/Cell-biology/cit3.htm

Golgi apparatus

• Formed of Golgi stack [saccules] ,transfere vesicles & secretory vesicles

• Has trans face [towards the rER] & cis face [towards the secretory surface]

• Stained for LM with silver

• Appear as –ve Golgi image with Hx & E in plasma cell & osteoblast

• Functions:

• Modification of proteins

• Sorting & packaging of proteins

• Recycling of cell membrane & membrane proteins

Glycogen

rER

Rough ER

rER • Flattened parallel cisterna continuous with each other & with nuclear

envelope & sER

• Present in protein secreting cells

• Appear as localized basophilia with L.M

• Function:

• Formation of secretory proteins , Lysosomal enzymes& membrane proteins

• Free ribosomes: • Formed in nucleolus as small & large subunits [ribonucleoproteins]

• In dividing cells

• Appear as diffuse basophilia

• Function: formation of cytoplasmic proteins

Rough & Smooth ER

RER

SER

RER SER

Smooth ER

sER

• Irregular reticulum of membranous tubules & vesicles

• Function:

• Carbohydrates & lipid metabolism

• Detoxification & Ca regulation

• Site: in liver cells, steroid forming cells, muscle cells

• Glycogen granules: • Alpha granules in liver rosette shaped

• Beta granules scattered in other cells [numerous in muscle]

• Stained with PAS

SER mitochondria

Secondary lysosomes

lysosome • Stained by histochemical staining [acid phosphatase technique]

• Iry lysosome: homogenous less acidic [inactive]

• 2ry lysosome: heterogenous more acidic [active]

• Types of 2ry lysosomes:

• Heterolysosome, autophago lysosome & multivesicular body

• Old residual bodies accumulated in cytoplasm form lipofuscin pigment

• Peroxisome • Contain catalases & amino acid oxidases

• Numerous in liver & kidney cells

• Originate by fission [also mitochondria originate by fission]

• Function: degradation of substances in liver & kidney e.g. alcohol & formaldehyde

• Formation of H2O2

• Beta oxidation of Fatty acids

Axoneme

Dynein arms

Microvilli

cilia

Basal bodies

Basal body [9 triplets of microtubules]

Cilia

Basal body

mitochondria

cilia

Basal body axoneme

Microvilli

Terminal web

Cell coat [Glycocalyx]

Microvilli and terminal web

Axoneme Basal Body

Cilia • Axoneme [shaft ] of cilia :

• Formed of 9 doublets & 2 singlets of microtubules • Motility is Dependent on dynein motor protein [consume ATP] • Basal body: similar to centriole [9 triblets] of microtubules • Cilia are long , motile • Cells carry 200-300 cilia

• Microvilli • Shorter , immotile • Cell carry 1000-3000 microvillus e.g. absorptive intestinal cells • Its core formed of actin filaments • Attached to terminal web of actin filaments • Have well apparent cell coat • Appear as brush border with L.M • Stereocilia are Long microvilli

centrioles

Centriole

Scanning EM for cilia and microvilli

Centriole during mitosis

Microtubules and microfilaments

Microtubules

Cytoskeleton • Formed of microtubules, intermediate filaments & thin filaments [actin or

microfilaments]

• Microtubules: • formed of tubulin protein arranged in 13 protofilaments

• Microtubules & actin filaments are polar structures [has -&+ ends]

• Microtubules are assembled at MTOCs e.g. centrioles ,basal body of cilia,& kinetochore of centromere

• Stained with anti tubulin fluorescent antibody [immunohistochemical staining]

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Mitochondria Cell junction

sER

2ry Lysosomes

Primary lysosome

Secondary lysosome

Glycogen granules

StemCells in tissue culture

Stem cells • Undifferentiated cells with unlimited capacity of self renewal

• Characterized by plasticity in tissue culture

• Bone marrow contain 2 types of stem cells: mesenchymal & hemopoietic stem cells

• Sources of stem cells:

• Bone marrow aspiration, umbilical cord blood

Epithelium

Microvilli

Basal infoldings

Basal region of ion transporting cell

Basement membrane

Terminal web

Zonula adherence

Macula adherence

Junctional complex • Present between epith cells lining GIT

• Formed of zonula occludense , zonula adherense & desmosomes

• Zonula occludanse & adherense attach to actin filaments of terminal web

• Macula adherense [desmosomes] attach to intermediate filaments [keratin filaments or tonofilaments] of cytoskeleton

Mucous acinus

Goblet cell

Pseudostratified columnar epithelium

Basal cell

Goblet cell (“TEM”)

• electron lucent

mucous granules •Golgi •rER

Secrete mucous More numerous in large

intestine

Taste Buds (neuroepithelium)

Taste pore with microvilli

Basal (stem cell)

St, sq.ep.of the dorsal surface

of the tongue

Supporrting cell

Receptor cell

Connective Tissue

Macrophage

Pseudo podia

Lysosomes

Vacuoles

• Macrophges originate from blood monocytes

• Act as antigen presenting cells

• Have different types in different tissues: 1. C.t macrophage [Histiocytes]

2. Kupffer cells in liver

3. Microglia in CNS

4. Langerhans cells in skin

5. Osteoclast in bone

6. Alveolar macrophage in lung

Macrophage

Plasma Cell

• Origin of plasma cells:

• Activated B lymphocytes

characteristics: 1. Negative Golgi image

2. Rich in rER [deeply basophilic cytoplasm]

3. Nucleus: peripheral chromatin clumps leading to cart wheel appearance, clock face appearance

• Plasma cells are antibody forming cells.

Plasma Cell

Plasma Cell

Collagen fibrils beside a fibroblast

Collagen and fibroblast

Collagen fibrils

Elastic and collagen fibers

Collagen fibers: • Characterized by axial periodicity

• Formed of tropocollagen

• Stained by Mallory , Maison stains

• Type I: in c.t. proper & bone

• Type II in cartilage

• Type III in reticular fibers

• Type IV in basal lmaina

• Elastic fibers: • Formed of amorphous protein [elastin] surrounded by fibrillar protein

[fibrillin]

• Stained with Orcein stain & Van Geison stain

Elastic (elastin and microfirillar protein)

Mast Cell

Coarse electron dense granules

Mast cells • Its granules are stained metachromatically by toluidine blue

• Granules contain: histamin , heparin , SRSA, neutrophilic & esinophilic chemotactic factor

• Has antibodies IgE attached to its surface

• Cause local hypersensetivity reactions

Mast Cell

Unilocular Fat Cell

Fat droplet

Fat droplet

Mast cell pericyte

Blood capillary

Multilocular Fat Cell

Fat cells

• Function of unilocular fat cell & white fat:

• Fat storage

• Support organs [perinephric fat around kidney]

• Heat insulation

• function of multilocular fat cells & brown fat:

• Heat production [thermogenesis]

Haversian canal

Osteocytes inside lacuna

Concentric lamella

Interstitial lamella

osteoblast

Osteocyte

Osteocytes • Osteoblasts & osteocytes are non dividing

• Function of osteocytes is to keep the integrity of bone

• Its processes are present inside canaliculi

• Osteoclast: • Multinucleated cell originate from blood monocyte

• Present in endosteum inside Howship’s lacuna

• By E.M. has 4 zones:

• Ruffled border, vesicular zone , clear zone & basal zone

• Osteoclasts & osteoblasts are responsible for bone remodeling

Osteoclast

Osteoclast Ruffled border

Multiple nuclei

Muscular Tissue

Myofibrils – Sarcomer – T tubule

mitochondria

Glycogen granules

Cardiac muscle

Intercalated disc

Intercalated discs

• Transvers portion of intercalated disc contain the following junctions:

Fascia adherense , macula adherens, &

gap junctions

• Longitudinal portions of intervalated disc contain gap junction only

• Skeletal muscle: • Triads [2 cisterna & T tubule] pass at A I junction

• Cardiac muscle: • Diads at Zline

Smooth muscle Central portion containing: Mitochondria, Golgi app. ,rER & glycogen

Peripheral region contain :

Myofilaments & dense bodies

Intercalated disc

Nervous Tissue

Nerve cell

Axon & Myelin

• Axoplasm contain:

Microtubules {neurotubules},filaments, mitochondria, few sER but NO ribosomes or rER

• c.t. inbetween nerve fibers in peripheral nerve is called endoneurium

• Myeline is formed by fused Schwann cell membrane

• Peripheral nerve fibers: all have neurilemmal sheath

Myelinated nerve fiber

myeline

microtubules

Collagen fibers

Unmyelinated nerve fibers within cytoplasm of Schwann cell

Collagen fibers [preticular fibers] &fibroblast

RBC

platelet

Capillary Endothelium

Rbcs

• Its elasticity due to Support of the cell membrane by cytoplasmic lattice of Spectrin & Ankyrin proteins

• Its cell coat glycoprotein carry antigens of A,B & Rh types

Neutrophil

Neutrophile

Segmented nucleus

Neutrophil

Neutrophil

• Neutrophile contain 3 types of granules

• Neutrophile also called:

• Polymorphonuclear leukocyte & microphages

• Nonspecefic [azeurophilic] granules are lysosomes

• Specific [neutrophilic] granules contain :

• Alkaline phosphatase, collagenase& lactoferrin

• Tertiary granules contain collagenase enzyme. • Neutrophile act against acute bacterial infections

Eosinophil

Granules

bilobed

Crystaline electron dense core

• Esinophil specific granules have central electron dense core[internum] surrounded by less dense called [externum]

• Internum contains:

1. Major basic protein

2. Esinophil cationic protein

3. Neurotoxin

• Externum contains :hydrolases, peroxidase enzyme & phospholipase

• Esinophiles have bilobed nucleus

• Esinophiles act against parasites & hypersensetivity

Eosinophil

Basophil

basophil

Basophil

Platelet

Platelets

Microtubule rings

• Platelets originate from megakaryocytes

• Platelets stained with cresyl blue stain

• Has central granulomere contain 3 types of granules: 1. Alpoha: contain fibrinogen, platelet growth factor& thromboplastin

2. Delta: contain ADP, ATP & calcium & serotonin

3. Lambda: lysosmal enzymes

• Has peripheral hyalomere containing: 1. Microtubule rings

2. Dense & surface connected membranous tubular system

3. Actin & myosin

Platelets

Blood Vascular

Pinocytic vesicles

Continuous capillary

Tight junctions

Fenestrated Capillary

Fenestra with diphragm

• Endothelial cells are continuous and joined by tight junctions

• Have pinocytic vesicles for transport [transcytosis]

• Present in skeletal muscles & barriers

• Fenestrated capillaries with diaphragm: • Present in endocrine glands & intestine

• Fenestrated capillaries without diaphragm in glomerular capillary of kidney

• Pericyte • Capillaries are surrounded by pericyte [originate from UMC]

• Function : Regeneration

• control capillar blood flow [contractile]

Continuous capillary

histology em

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