Subculture of Vero cells - Tissue Culture (Jul/10/2009 )

Hi friends, can any one suggest for culturing vero cell line. I use Invitrogen IMDM 10% FBS containing 3 gm/ L sod. Bic.I used to split the confluent flask t0 1:1. Daily it become confluent. after 3-4 Passages, these cells has some granular particle, form vacoules and didn't grow thereafter. Why these granular formation occurs. How to avoid it.

Your cells have senesced, culture at a lower density, and ensure they don't become confluent.