Abstract: An assembly and components therefor are disclosed for use in the field of cell and tissue culture. The assembly includes a base having one or more wells, and a cell culture insert which is mountable to the base such that the bottom wall of the insert is suspended within the well. Each well has a generally rectangular configuration such that openings are provided at each corner of the well for introducing fluid to the well. The base includes stepped portions for supporting a pair of flanges extending from diagonally opposite sides of the cell culture insert. A cover is provided for protecting the assembly and maintaining the position of the cell culture insert.