OBSOLETE cambium-like transitional zone true OBSOLETE. A cup-shaped region in the shoot apical meristem found between the central mother cell and the rib and peripheral zone. The cells of this zone are derived from the corpus intials, but in some cases they arise also from tunica initials. 形成層様移行帯 (Japanese, exact) ventral meristem (related) PO:0006067 plant_anatomy adaxial meristem (related) leaf meristem (related) zona transicional semejante al cambium (Spanish, exact) If found, this zone is a temporary feature mostly in Gymnosperms.