is the general name for the removal of cells, tissues or organs from an animal or plant and their subsequent placement into artificial environment conductive to growth
Tissue culture
When the cells are removed from the organ fragments, thus disrupting their normal relationship with neighboring cells
Cell culture
Cultures of animal cells are usually divided into 3 classes:
- Primary
- Cell strains
- Cell Lines
considered to be more physiologically similar to in vivo cells
Primary Cells
have a finite
lifespan of 5-10 divisions in vitro, thus long-term
experiments are discouraged
Primary culture cells
This step covers from preparing tissue to isolating and plating cells in dishes
Isolation
2 basic methods for obtaining primary culture
Explant culture
Enzymatic dissociation
Small pieces of tissue are
attached (using plasma clots or
fibrinogen) to a glass or treated
plastic culture vessel and
immersed in culture medium
Explant cultures
-More widely used
-speeds up the process by adding
digesting (proteolytic) enzymes
such as trypsin or collagenase to
the tissue fragments to dissolve
the cement holding the cells
together
Enzymatic dissociation
-Cells will continue to grow and divide normally for a limited number of passages
Hayflick’s Phenomenon
In Hayflick’s Phenomenon, The number of passages decreases
when….
cells are harvested from older
individuals
If the cells in a cell strain undergo a transformation
process (spontaneous or induced changes in karyotype,
morphology or growth properties) that makes them
“immortal“ (able to divide indefinitely) they are called
Cell line
often have abnormal chromosome numbers
and maybe tumorigenic when inoculated into susceptible
animals
Cell lines
Cell lines that have been derived from tumors often do not
exhibit contact-inhibition (inhibition of growth under
crowded conditions), but rather….
continue to pile-up
cells that have been adapted to
culture but, unlike cell lines, have a finite division
potential
Cell strains
Upon serial transfers of primary cells, a _________ may occur until a particular cell type
becomes predominant
gradual selction
If these cells continue to grow at a constant rate over
successive passages, these primary cells are
referred to as a
Cell strain
Cell strains have a finite lifespan of ___________ in
vitro
40-60 divisions
Some of these cell lines have actually been derived
from tumors or are transformed spontaneously in
culture by
mutations
________________ treated cells can become
infinite with loss of growth factors
Chemical or gamma ray
Cells may be loosely divided into
two main types
-Adherent cell culture
(Anchorage-dependent)
-Suspension cell culture
(Anchorage-independent)
- Form monolayers
- e.g. cells derived from different
tissue (breast, liver) - Growth is limited by surface area
Adherent cell culture
(Anchorage-dependent)
- derived from cells which can divide and survive without being attached to a substrate,
- e.g. cells of haemopoietic lineage
- Can be maintained in culture vessels that are not tissue-culture treated
- requires agitation for adequate gas exchange
- Easier to passage
Suspension cell culture
(Anchorage-independent)
________ in attachment culture have a characteristic growth cycle similar to bacteria
Eukaryotic cells
