A cavity in the secondary cell wall, allowing exchange of substances between adjacent cells. A pit consists of a pit cavity (the aperture in the secondary wall) and a pit membrane (the primary wall material adjacent to the cavity). Pits usually occur in pairs (pit pairs), the members of the pair being situated in adjacent cell walls. There are two main types of pit, * simple and * bordered. Though a pit in a secondary cell wall is distinct from a cavity in a primary cell wall (* primary pit field ), it is often difficult to distinguish between the two and then the term pitted is used for either structure. See also plasmodesmata. |
