Title: Anatomy / histology

Q: The cell in histology and labs
A: Eucaryotic cells contain a nucleus (found in protists (protozoa e.g amoebas, algae, slime and mold), plants, animals, fungi), while procaryotic don`t (found in bacteria and archaea).
In a lab, they can be grown in cell culture flasks and petri dishes. Fluorescent agents are added, they are not naturally fluorescent.
With immunocytochemistry you can visualize more specific structures. The downside of the method, you can only see what you already know and what you have antibodies for.
Difference SEM -> 3D, vs TEM -> 2D.

Q: cell facts + size
A: - procaryot and eurcaryot
- prototzoa (Einzellige) and metazoa (Mehrzellige)
- cell membrane and cell nucleus
- basic element of the human body
- 75x10^12 cells, 75 trillion
- size between 5 and 150 µm
- homeostasis – turnover of cells of approx. 50 Mio per second (eg. brain approx. 100.000 cells per day)
- approx. 200 different types of cells

Q: cell properties
A: Cells can be differentiated in 3 main properties:
1 metabolism, energy generation
2 proliferation, limited lifespan
3 perception, respons to stimuli

Q: cell membrane
A: It is not rigid, but fluid and can even form bubbles. It is made out of (phospho)lipids and an outer protein layer (and cholesterin). The layers are hydrophilic - lipophilic (hydrophobic) - hydrophilic.
The two sides are connected by different types of ion channels.
The nucleus is surrounded by a secondary layer of membrane. Inside of the nucleus we find the DNA (amino acids). We need 20 +(2) amino acids in total.

cell organelles

Q: mitrochondria
A: = power house of the cell
endosymbiotic theory: procariotes were taken up by the cell, have their own genes

Q: DNA
A: The DNA is in control of internal processes of the cell and responsible for heredity. Every cell in an organism contains the same DNA.

Q: Cell proliferation
A: Mitosis and meiosis are both types of cell division, but they serve different purposes and have distinct processes.
mitosis: 2 identical diploid daughter cells
meiosis: 2 splitting cycles, 4 haploid genetically different cells (sperm/egg cell)
PMAT ( Prophase, Metaphase, Anaphase, Telophase)

Q: Imaging - Cytochemical & Histological Methods
A: Cytochemistry: Detection of chemical components (antigens) in cells.
Histology: Study of tissue structure with dye aggregation.
Histochemistry: Uses chemical reactions to highlight tissue components.
Immunohistochemistry: Uses antibodies to detect proteins in tissues.

Q: types of microscopy techniques
A: LM:
- bright field
- phase contrast
- interference contrast
- dark field
EM:
- SEM
- TEM

Q: light microscopy
A: using a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects
- Bright Field: Standard method where light passes through the specimen; best for stained samples.
- Phase Contrast: Converts phase differences into contrast, making internal structures visible in live, unstained cells.
- Interference Contrast: Uses polarized light to create highcontrast, 3D-like images; great for detailed views of live cells.
- Dark Field: Blocks direct light, showing the specimen bright against a dark background; ideal for small, unstained objects

LM

Q: electron microscopy
A: Scanning Electron Microscopy (SEM) Surface imaging.
Transmission Electron Microscopy (TEM)  Internal structure imaging.

Q: Radiology-Based Imaging
A: Micro-Computed Tomography (µCT)
 Magnetic Resonance Imaging (MRI)

Q: Live vs. Fixed Cell Imaging
A: Live Cell Imaging: Observing metabolic processes in real-time.
Fixed Cell Imaging: Uses fixation methods (formalin, paraffin, cryosections) to preserve tissue for long-term analysis.

staining of live/dead cells

Q: Confocal Microscopy & ZStacking
A: Captures optical slices of a sample without interference from other layers.
Creates high-resolution 3D reconstructions.

Q: Advanced Tracking Methods
A: Genetically Engineered Fluorescent Proteins:
 GFP (Green Fluorescent Protein)
 RFP (Red Fluorescent Protein) for long-term cell tracking.

Q: Goals of Labelling
A: Detect, localize, and analyze:
Specific structures (e.g., membranes, organelles).
Secretory products (e.g., enzymes, metabolites).
Molecules within cells and tissues.

Q: Common Labelling Techniques
A: Vital stains: Differentiate live and dead cells.
Fluorescent dyes: Track cell components (e.g., Calcein for cytoplasm, DAPI for nuclei).
Autofluorescence: Some biological components naturally fluoresce under UV/blue light.
Phalloidin staining: Used for actin filaments in cell migration studies.
Immunohistochemistry: Detects proteins using antibodies.

Q: histological sample processing
A: Paraffin-Based Histology
1. Fixation (Formalin)
2. Dehydration (Alcohol)
3. Infiltration & Embedding (Xylol & Paraffin)
4. Sectioning & Staining
Cryohistology
Tissue is frozen instead of embedded in paraffin.
Maintains enzyme activity for histochemical analysis.

Q: specialized staining techniques - Enzyme & Chemical-Based Staining
A: Alkaline Phosphatase Staining - Identifies enzyme activity.
PAS (Periodic Acid-Schiff) Staining - Highlights mucopolysaccharides.
MSB Staining - Differentiates fibrin, collagen, and erythrocytes.

Q: Specialized Staining Techniques - Immunohistochemical Staining
A: Uses antibody-antigen interactions to detect proteins.
Examples:
Ki-67 :  Cell proliferation.
Caspase 3 : Cell death.
Osteocalcin : Bone formation.
SMA/CD31 : Blood vessel markers.

Q: Hard Tissue Histology & Implant Integration:
Challenges with Bone & Metal Implants
A: Requires decalcification for soft tissue histology.
Uses resin embedding & grinding sections for implants.

Q: Hard Tissue Histology & Implant Integration:
Stages of Implant Integration
A: - Day 0 - Blood clot formation.
- Day 4 - Granulation tissue formation.
- Day 14 - Woven bone formation.
- Day 28+ - Lamellar bone development.

Q: Additional Imaging Techniques
A: Bioluminescence Imaging
Uses luciferase-based reporters to track gene expression in living organisms.
Lectin Staining
Binds specific carbohydrates to analyse tissue glycosylation patterns.
Used in biomaterial development & tissue regeneration studies.