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Enzyme histochemical staining
- Identification of specific enzyme or enzyme activity using enzyme substrate
- sections incubated with substrate
- enzyme reacts with substrate
- reaction is visualized with color reagent in subsequent step
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Immunohistochemistry
Identification of specific cellular or extracellular components using specific antibodies
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Trichrome
 - Three different dyes
- e.g., Can be used to evaluate fibrosis, status of elastin fibers
- Elastin = dark purple / black
- Collagen = blue
- Muscle = red
- RBC = Orange
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Silver Staining
- (various methods)
- Can be used to stain various cells, cellular structures and/or microorganisms
- e.g., Basal laminas, reticular fibers
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Periodic Acid-Schiff (PAS)
- Stains simple and complex carbohydrates deep magenta
- microvilli-sugar rich cell coat
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Hematoxylin
- Nucleic Acids BLUE
- a. A "basic" dye (i.e., positively charged)
- b. Attracted to negatively charged molecules (e.g., nucleic acids)
- c. Color = BLUE
- d. Examples of staining: nucleus, rough ER
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Eosin
- a. An "acidic" dye (i.e., negatively charged)
- b. Attracted to positively charged molecules (e.g., proteins)
- c. Color = RED
- d. E.A.R. (Eosin - Acid - Red)
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electron micrograph
bi-layer nature key to compartmentalizing can be appreciated with electron micrograph
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mitochondria
- Energy Production
- Cell Death
- Ca2+ Storage
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Smooth Endoplasmic Reticulum
- SER is More abundant in some cells versus others.
- It is the site of lipid and steroid synthesis
- The site of drug detoxification
- (Example: cytochrome P450 which is abundant on the sER in the Liver).
- It is important In muscle, for storage & release of Ca2+ (sarcoplasmic reticulum)
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Perioxisome
- Membrane-bound spherical Organelles
- contain oxidative enzymes like catalase
- Fatty Acid Metabolism
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Nucleus
- contains most of the cell’s DNA (mitochondria contain some too) as well as RNA and proteins.
- Surrounded by 2 lipid bilayers.
- Areas of active transcription are called “Euchromatin” (E).
- Areas of little or no active transcription are called “Heterochromatin” (H).
- These can be seen ultrastructurally.
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Four types of tissue
- Epithelium
- Connective
- Muscle
- Nerve
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Epithelium Functions
- -Barrier
- Cover exterior surface (skin, eye)
- Line tubes that connect inside and outside (gut, respiratory)
- Line internal cavities of the body (peritoneum, pleural cavities, bladder)
- -Absorption (intestine)
- -Secretion (salivary or sweat glands)
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Typical Epithelium
- 1. Cells ordered and close together
- -connections between cells
- -communication (gap junctions)
- 2. Polarity
- -functional
- -structural-"hats"
- 3. No direct blood supply
- 4. Resting on a basement membrane
- 5. Separated from connective tissue
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Epithelium Classification
- Epithelia are classified by cell shape and cell arrangement on the surface layer
- Cell layers
- Simple(1 layer thick)
- Stratified (2 or more layers thick)
- Cell height and shape
- Squamous
- Cuboidal
- Columnar
- Cell height and Shape (the funky category)
- Pseudostratified
- Transitional
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Epithelial Classification Table
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Epithelial Features that dictate function
- Polarity
- Communication
- Adhesion
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Basement membrane
- part of the extracellular matrix
- Description
- Band of amorphous extracellular substance
- (50-100 nm thick)
- Separates all epithelium from underlying connective tissue
- Hard to see by conventional light microscopy
- Consists of:
- Type IV collagen
- Proteoglycans (heparan sulfate, chondroitin sulfate)
- Glycoproteins (laminin, fibronectin, entactin)
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Basement Membrane components
- Type IV collagen
- Proteoglycans (heparan sulfate, chondroitin sulfate)
- Glycoproteins (laminin, fibronectin, entactin)
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Basement Membrane Function
- CRITICAL for normal epithelial cell structure and functiion
- -Anchor for epithelial cells
- Adhesion sites = hemidesmosomes
- Separates all epithelium from underlying connective tissue
- -Compartmentalization
- Separates epithelia from connective tissue
- -Filtration & Diffusion
- Epithelia is not vascularized
- -Polarity
- Induces formation of polarity (basal to apical)
- -Scaffolding
- Guide for embryogenesis, tissue regeneration and wound healing
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Microvilli
- Actin filaments
- Increase surface area for absorption (e.g., small intestine)
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Cilia
- Microtubules (9 + 2 arrangement)
- They've got the beat (e.g., trachea, bronchi, oviducts)
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Microtubules – The Axoneme
- Extends from a basal body
- 9 + 2 arrangement of microtubules oriented longitudinally
- Center is 2 complete microtubules surrounded by 9 doublets
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Tight Junctions
- (zonula occuludens or occluding junctions)
- Located apical
- Polarity (establish functional biochemical domains)
- Physical barrier
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Adhering Junctions
- zonula adherens
- Band around cell
- With-stand physical stress
- Interact with ACTIN filaments
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Desmosomes & Hemidesmosomes
- (macula adherens or attachment plaques)
- Spot or disc connections
- Interact with INTERMEDIATE filaments
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Gap Junctions
- Pores made from connexon
- Couples cells electrically and metabolically
- e.g., movement of Ca2+, cAMP, amino acids, etc.
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Glands
- Derivatives of epithelial tissue involved in secretion of products
- Classification: Secreted product
- ENDOCRINE
- Secrete directly into blood stream (e.g., hormones, steroids)
- Surrounded by blood vessels. (No ducts)
- EXOCRINE
- Product secreted into duct or tube (e.g., salivary, pancreas)
- Mucous: viscous glycoproteins
- Serous:"watery" protein secretion
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Gland Structure Classification
- -Unicellular
- e.g., mucous or goblet cell
- -Multicellular
- Simple glands (no branches)
- Compound glands (branches)
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