The number of cells in the cerebrospinal fluid increases after death. It is not clear whether this observation represents a post-mortem or a supravital phenomenon. There is speculation that some of the cells actively enter the cerebrospinal fluid during the first hours after death and that the rest exfoliate from the subarachnoid layer. The post-mortem cell count in cerebrospinal fluid correlates to the time after death and can be described mathematically (polynomial curve of third order).