Exam 1 Microanatomy Thread Flashcards
Phase Contrast
Microscopy
Small differences in refractive index ⇒ difference in contast.
Darkfield Microscopy
Specimen illuminated at an angle.
Curved surfaces scatter light.
Increases contrast of small objects in unstained specimen.
Polarizing Microscopy
Only rotated light visible.
Useful for visualizing structures that are arranged in a cystalline or paracrystallin array.
Confocal Microscopy
Opectical section of unsectioned specimen.
Laser excits cells in thin plan.
Out of focus regions are excluded ⇒ sharp image.
Hematoxylin & Eosin
Stains according to net charge at pH of staining solution.
Hematoxylin (+) charge so stains (-) charged tissues ⇒ basophillic
DNA/RNA
Proteoglycans & GAGS
Nucleus/Nucleolus
Ribosomes and RER
Eosin is (-) charged and stains (+) charged tisues ⇒ acidophillic
Mitochondria
Lysosomes
Erythrocytes
Collagen
Secretory vacuoles
Cytosol (proteins)
Trichrome Stains
Stains collagen
Masson trichrome ⇒ greenish blue
Mallory trichrome ⇒ sky blue
Elastic Stains
Aldehyde fusion
Orcein
Weigert’s elastic stain
Silver Stains
Reticular Fibers
Carbohydrate Stains
Periodic acid-Schiff (PAS)
Best’s Carmine
Lipid Stains
Oil Red O
Sudan black
Osmium tetraoxide
Stains Summary
Glycocalyx Funtions
- Recognition
- Enzymes
- Immune recognition signals
- Receptors
- Transporters
- Components of channels
Inclusions
- Glycogen
- No membrane
- PAS or Best’s Carmine stains
- Lipid droplets
- no membrane
- Lipofuschsin
- Melanosomes
Nucleolus
Formed around nucleolar organizer regions (NOR).
Assembles signal recognition particles (SRPs)
Nucleus Transport
Nuclear pores are open aqueous channels ⇒ small (9-11nm) molecules passively diffuse
Larger proteins with nuclear localization signal (NLS).
Work with Exportins and Importins
Nucleus and Cell Division
- Lamins phosphorylated ⇒ nuclear lamina and pore complexes disassembled
- Dephosphorylation of lamins ⇒ repolymerize on chromosomes
- Vesicles fuse around chromosomes or groups
- Chromosomes come together, membranes fuse into one
Mitochrondria Function
Calcium sequestration
Apoptosis role
Thermogenesis
Energy generation
Enzyme histochemistry with succinic dehydrogenase.
RER
- Protein synthesis and modification
SER
- lipid and steriod synthesis
- detoxification of lipid soluble drugs and toxins
- sequesters Ca2+
- role in glycogen metabolism
Golgi
Proteins/Lipids made in ER modified and sorted in golgi.
Large cytocentrum/centrosome ⇒ active golgi
Lysosomes
ID with acid phosphatase
Primary ⇒ enzymes, no substrates
Secondary ⇒ active enzymes and substrate
Tertiary ⇒ little or no rsidual enzyme activity, undigested substrates
Peroxisomes
Oxidation of long-chain fatty acids, bile acids, ethanol, and cholesterol.
ID with catalase.
Some with crystalloid of urate oxidase but not humans.
Formed de novo via pre-peroxisomal vesicles from ER
or from pre-existing peroxisomes via fission mediated by Pex proteins or peroxins
Cytosolic Protein Filaments
Overview
Microtubules
- Filaments formed of heterodimers
- Beta tubulins at (+) end
- Alpha tubulins at (-) end
- (-) end of the MT centralized near the nucleus at the MOC
- Dynamic instability
- growth and shrinkage at either end but more easily at (+) end
Microtubule Associated Proteins
(MAPs)
- Organize microtubules
- Stabilize, anchor, and space MTs
- Regulate MT interactions with other elements
- Regulate MT stability and dynamics
- Ex. Tau, MAP1A, MAP2, MAP4, Katanin
Tau & Alzheimer’s Disease
- Tau modulates stability of axonal microtubules
- Hyperphosphorylation of Tau can result in disassembly of microtubules
- Hyperphos tau form complexes ⇒ neurofibrillary tangles
Microtubule
Motor Proteins
Dyneins ⇒ move from + to - ends
Kinesins ⇒ move from - to + ends
Mitotic Spindle
- Chromosome kinetochores captured by (+) end of MT
- Moved to poles by MT dynamics and motor proteins
- Spindle pole (aster) and spindle fibers allow for seperation of daughter chromosomes and daughter cells.
- Chromosome-located kinesin help draw daughter chromosomes to spindle pole
- Spindle fiber kinesins push daughter chromosomes apart
Microtubule Organizing Center
(MTOC)
Centrosome is the main MTOC.
- Site of nucleation
-
γ-tubulin is only found in centrosome
- required for nucleation
- Nucleated at minus end
MT
Accessory Proteins
Anchor MT
Sever and release MT from centrosome
Provides scaffolds and adaptors for other proteins to link to centrosome
Centrioles
- Embedded in centrosome
- Organize centrosome (pericentriolar) matrix
- Become basal bodies in cilia and flagella
- Proximal part of lumen lined by α-tubulin
- provides template for nucleation and arrangement of MT triplets
- Distal part of lumen with centrin
- Proximal and distal connecting fibers connect pair
- 9x3
Basal Bodies
- Formed from centrioles
- Located at base of cilia and flagella
- 9x3+0
Motile Cilia and Flagella
- 9x2+2 arrangement
- Ciliary dynein provides movement
Nodal cilia
Found in embryo @ gastrulation
9x2+0
beat clockwise
Primary Cilia
- Non-motile
- Found on almost all eukarytoic cells
- 9x2+0
- Act as mechanosensors and chemosensors
Keratins
Intermediate filament specific to epithelial cells.