Studies on the Ultrastructure and Mechanism of Secretion of the Salt Gland of the Grass Spartina

As previously reported the basal cell of the salt gland in Spartina is partitioned by a system of paired membranes (Fig. 1, arrows). These membranes are infoldings of the plasmalemma which extend inward from the wall protuberances located on the wall between the basal and cap cell (Fig. 1, p). The long extracellular channels between the partitioning membranes are open to the wall protuberances and thus open in the direction of secretion. The channels are closed at the terminal ends deep within the cell. The partitioning membranes appear to be analogous geometrically to surface membranous channels in absorptive and secretory cells in animal tissues. Because of this remarkable similarity we have suggested that the standing-gradient flow system of solute linked water transport elucidated by Diamond and his associates 2-3 is the probable mechanism of fluid transport and secretion in the salt glands of Spartina.