these changes could be classified into four broad stages : i ) cells were flattened , closely attached to one another and microvilli appeared , ii ) cells rounded , microvilli began to disappear and the cells started to separate from one another by cytoplasmic strands , iii ) cells were discrete , rounded structures and iv ) cells were rounded and had numerous attached buds , some of which contained virus .
C0026049
microvilli
C0007634
cells