<prompt> The total volume of CSF in an adult is about -100-150 ml300-350 ml500-550 ml600-650 ml  <response>: Ans. is a i.e., 100-150 ml o The major source of CSF is the choroidal plexus of all 4 ventricles, mainly in two lateral ventricles, o Other sources of CSF are ependymal cells of the ventricles and the brain itself, via perivascular spaces, o The total volume of CSF in an adult is about 125-150 ml. o The rate of formation of CSF is about 500-550 mlday. Thus the CSF is replaced 3-4 times every day. 