Apparatus for Percoll microgravimetry determinations in experimental brain edema.

A microgravimetry apparatus is described which utilizes osmotically-balanced Percoll gradients produced by a computer-driven low pressure gradient system. A plexiglass reservoir was designed to minimize parallax artifacts while allowing repeated measurements and easy retrieval of groups of 20 samples. This system provides inert and nontoxic gradients with profile flexibility, reproducibility, and longevity when used for the routine gravimetric measurement of edema in 30-mg central nervous system tissue fragments.