Abstract: A chamber has a lid that permits opening and closing of the chamber for inserting or removing a cell culture from the chamber while the chamber is in a stack of chambers without removing any of the chambers from the stack. The lid of the chamber may have one or more ports which enable substances to be introduced into or removed from the chamber when the chamber is sealed by the lid. In one embodiment, the lid is a side wall of a rectangular chamber in a stack of rectangular chambers. Spacers may be provided between the chambers of the stack to provide space between the chambers and restrict horizontal movement of the chambers relative to each other. A flexible container containing an atmosphere may be connected to a port of the chamber, and the atmosphere may be transferred to the chamber by compressing the flexible container. After a cell culture is introduced into the chamber, the stack of chambers may be placed into an incubator.