The restriction point- point of no return. If cell passes this point it will divide. Usually late in G1. Cytoplasm to genome ratio. Cell will not pass the restriction point if there is not enough cytoplasm.
Growth is inhibited if contacted on all sides.
HGH, growth factors. Control of Cell Division A. Timing and rate of cell division in different parts of an organism are critical to normal growth, development and maintenance. B. Different types of cells exhibit different patterns of cell division. Human skin cells divide frequently throughout the life span. Place dissociated cells in vessels containing a growth medium which includes the necessary glucose, amino acids, vitamins, salts, blood serum and antibiotics to support the cells in a bacteria free condition.