bundle sheath mestome sheath vaina del mestoma (Spanish, exact) plant_anatomy PO:0006025 メストム鞘、維管束鞘の内側、維管束鞘延長部 (Japanese, exact) The inner endodermal sheath of a two layered bundle sheath. The cells are smaller in diameter compared to those in outer wall (starch sheath). The cell walls are thick and contain suberized lamellae. They are analogous to endodermis.