Cytology introduction Flashcards
What is Cytology the study of?
Structure and function of cells
What is Histology the study of?
Studies tissues and microscopic structure of organs
What is Embryology the study of?
Fetal development of vertebrates
When was the first microscope made?
1590
Who created the first microscope?
Hans Lippershey and Sacharias Jensen
Who improved the first microscope and when?
Galileo Galilei improved the 1st microscope in 1610
Between 1611-1628, who made real prototype of the modern microscope?
Christopher Scheiner
Who examined the ‘cork’ using a similar microscope to Scheiner?
Robert Hooke
Who began to use the word ‘cell’?
Robert Hooke
What does the word ‘Histology’ split into?
Histos (tissue) + logia (scientific research)
Who proposed the term ‘Histology’ and when?
Xavier Bichat (1771-1802)
Who postulated cell theory?
Theodor Schwann and Matthias Schleiden
What are cells the basic unit of?
All life functions, exchange, movement, reactivity and continuity of information
What is each cell derived of?
Another cell
What year the ‘cell nuclei’ was discovered and by whom?
1825 - Jan Evangelista Purkyně
What year the theory ‘every cell comes from a cell’ was discovered and by whom?
1852 - Rudolf Virchow
Latin sentence for ‘every cell comes from a cell’?
‘Omnis cella e cullula’
What year ‘nucleic acids’ were discovered and by whom?
1869 - Friedrich Miescher
What year ‘mitosis’ was discovered and by whom?
1873 - Walther Flemming and Matthias Schleiden
What year ‘chromosomes’ were discovered and by whom?
1874 - Bugli and 1875 -Edouard Van Beneden
What year ‘centrioles’ were discovered and by whom?
1885 - Theodor Boveri
What year the ‘internal reticulum’ was discovered and by whom?
1886 - Camillo Golgi
What year range ‘meiosis’ was discovered and by whom?
1887-1889 - Edouard van Beneden and Theodor Boveri
What year ‘mitochondria’ were discovered and by whom?
1894 - Richard Altman and Carl Benda
What year range ‘proteins and amino acid organisation’ were discovered and by whom?
1899-1908 - Emil Fisher
What is cytochemistry?
The chemistry of living cells, especially as studied microscopically.
What is Histochemistry?
The branch of science concerned with the identification and distribution of the chemical constituents of tissues by means of stains, indicators, and microscopy.
What is Immunocytochemistry?
Technique that assesses presence of a specific protein/antigen in cells by use of a specific antibody, which binds to it, so allows visualisation and examination under a microscope.
What is Immunohistochemistry?
Powerful microscopy-based technique for visualising cell components, e.g proteins/ other macromolecules in tissue samples.
What is electron microscopy?
Technique to obtain high resolution images of biological and non-biological specimens. It’s used in biomedical research to investigate the detailed structure of tissues, cells, organelles and macromolecular complexes.
Compare cell and tissue culture?
Cell culture - cells are grown under lab conditions in vitro. Tissue culture - growing tissue by transferring them into an artificial environment in which they can continue and function.
What are hybridisation techniques used for?
Detect particular sequences (target) within a complex mixture of DNA/RNA molecules. DNA/RNA are usually transferred and immobilised to nitrocellulose or, more commonly, to nylon membranes.
What is considered development in science?
Accumulation of large amounts of scientific data
What are tissues meant to do? List the specific functions.
Tissues are specialised to carry out different activities and specific physiological functions, e.g. Excitability, conductivity, contractility, absorption, assimilation, secretion, excretion, respiration, growth and reproduction.
What are the 4 tissue types?
Epithelial, connective, muscular and nervous
Function of epithelial tissue?
Covers all free body surfaces + protective and secretory functions
Function of connective tissue?
Penetrates all other tissue + supporting and protective function in organ construction
Function of muscle tissue?
Highly specialised for contractility + role in body part movement
Function of nerve tissue?
High specialisation of cells for conduction and contractility. Neurones connect the nervous system + body parts
Features of light microscopy?
- Routine
- Inverted
- Phase contrast
- Fluorescence
- Polarised + dark field
Features of electron microscopy?
- SEM
- TEM
- Fracture + Freeze etching
Formula for Magnification?
Magnification = Eyepiece x Objective lens
Describe the ‘inverted’ feature of the light microscope?
Light from top + objective lens at bottom. Very good for cell/tissue culture observations, including time lapse light microscopy of cells
Describe the ‘phase contrast’ feature of the light microscope?
Based on theory that light alters in speed when passing cellular + extracellular structures with different refractive indices (density). Image looks darker than surrounding background
Describe the ‘fluorescence’ feature of the light microscope?
Cell structures associated by means of histochemical/immunohistochemical technique with fluorescent dyes + observed microscopically with filters for a specific wave length
Describe the ‘polarising’ feature of the light microscope?
- Uses polarised light and used to observe crystals.
- Limited biological uses as cells are fragile and might die. - Also mostly colourless.
Describe the ‘TEM’ feature of the light microscope? [Transmission electron microscope]
Beam of electrons transmitted through ultra-thin specimen, interacting with specimen as it passes it
Describe the ‘SEM’ feature of the light microscope? [Scanning electron microscope]
Beam of electrons scanned over specimen to make a magnified image of object. The electrons interact with atoms in sample, to make various signals that have information about the sample’s surface topography + composition.
Describe the ‘freeze fracture’ feature of the light microscope?
- Specimen frozen rapidly and cracked on a plane through tissue.
- Fracture occurs along weak portions of the tissue such as membranes/organelle surfaces.
- After cleaving, both surfaces are shadowed with platinum film.
- This coating produces a replica of the surfaces.
What can electron microscopes examine?
- Living cells/tissues
- Thin material omentum/pleura
- Biological fluids and their cells
- Post-mortem tissue sample
- Biopsy material (to prep a permanent histological slide)
What are coagulative fixatives?
They remove water from tissues leading to coagulation and denaturalisation of proteins, mostly in the extracellular matrix, to fix material for light microscopy
Examples of coagulative fixatives?
- HSI
- Chromic acid
- Matanol
- Ethanol
When precipitates coagulate, what happens to proteins?
Denaturation
Are coagulative fixatives suitable for Electron microscopes?
NO
Examples of non-coagulative fixatives?
- Formaldehyde
- Glutaraldehyde
What do non-coagulative fixatives do?
Form inter and intramolecular changes of the solution from solution to gel.
What does Formaldehyde do?
Quickly penetrates tissue but easily removed with a few washes
What does Glutaraldehyde do?
- Slowly penetrates but permanently binds to proteins. - Cell membrane is partially permeable and osmotically active.
What must be done before colouring slides? (staining)
- Paraffin (waxy solid) removed from tissues by performing rehydration
- ^ As most usable dyes are soluble in water
How to use the protocol Hematoxylin/Eosin stain?
- After rehydration, place in hematoxillin for 20-40 mins.
- Lavage 1-5 mins (wash out of body cavity)
- Differentiation in Ethanol containing 1% HCl for 5 sec (removes excess paint + stains nuclei)
- Wash in water
- Stain in Eosin solution for 10 min. Lavage again
- Dehydrate + paraffin embedding
How to prepare for EM (postfixation)?
- Osmium tetraoxide = secondary fixative, as it associates with lipids, since it’s believed the unsaturated bonds of the FA are oxidised by it and materialized.
- It is an electronically dense black substance, that strengthens + increases contrast of sample.
