ENDOPLASMIC RETICULUM-DICTYOSOME INTERCONNECTIONS IN LIGULA CELLS OF ISOETES LACUSTRIS

Abstract

The sub-marginal ligula cells of I. lacustris, were investigated by EM. Their most conspicuous ultrastructural elements, a well developed tubular ER [endoplasmic reticulum] and a cisternal ribosomal ER and numerous active dictyosomes, indicate a high activity of protein synthesis and intracellular transport. Several dictyosomes show interassociations and partly direct interconnections with each other and with the tubular ER; the latter occurring at the fenestrated regions of the Golgi cisternae. The details, demonstrated by sections parallel and perpendicular to the cisternal planes of the dictyosomes, point to the existence of a functionally homogenous endomembrane system. Whether the endomembrane concept is of general validity or whether it needs to be restricted to the intracellular transport of secretion proteins is discussed.