(i) CDK (Cyclin Dependent Kinase) compounds provide external stimulation in interphase state.
(ii) Various hormones and growth factors provide internal stimulation during interphase.
(iii) Various metabolic activities continue in the cell during this stage. As the nucleus increases in size and many reactions take place, it is called metabolic nucleus.
(iv) DNA, RNA and protein synthesis takes place in this stage. Hence it is called synthesis stage.
(v) Chromosomes are arranged as chromatin.
(vi) In this state, the cells have the necessary energy reserves.
(vii) Increase in cell volume is greatest in this condition.
(viii) Duplication of the DNA of the cell takes place, i.e. the monad turns into a dyad.
(ix) Centrosomes of animal cells divide.
(x) This phase takes 90-95% time.