1. Continuous cell line

2. CELL LINES
When the primary culture is first subcultured or passaged then it becomes cell line.

3. TYPES OF CELL LINES
FINITE CELL LINES :- Normal cell usually divide only a limited number of times before loosing their ability to proliferate which is a genetically determined event known senescence these type of cell lines are known as finite cell lines
CONTINUOUS CELL LINES :- When a finite cell line undergoes transformation and acquires the ability to divide indefinitely then it is known as continuous cell lines.
TRANSFORMED CELL LINE:- It is defined as the conversion of a normal healthy into a tumorous or a cancerous cell

4. CHARACTERISTCS OF CONTINUOUS CELL LINE
Smaller, more rounded ,less adherent with a higher nucleus/cytoplasm ratio.
Fast growth .
Reduced anchorage dependence and grow more in suspension condition.
Ability to grow up to higher cell density.
Different in phenotype from donor tissue.
Stop expressing tissue specific gene.
Homogeneous cell population.
Serially propagated in culture showing an increased growth.

5. EXAMPLES OF CONTINUOUS CELL LINE
MORPHOLOGY
ORIGIN
SPECIES
AGE
CHARACTERISTICS
A2780
Epithelial
Ovary
Human
Adult
Chemosensitive with resistant variants
Vero
Fibroblast
Kidney
Monkey
Viral substrate and assay
IMR-90
Lung
Embryonic
Susceptible to human viral infection
WI-38