Rough endoplasmic reticulum

Appears as cisternae with membrane-bound ribosomes

Functions in the synthesis of specific proteins & lipids

Endoplasmic reticulum (together with the Golgi apparatus) is part of the endomembrane system of the cell, and there are two forms that can be found: rough ER (granular), and smooth ER (agranular); the latter is less common in plants. The granular appearance is due to the attachment of ribosomes to ER membranes.

Rough endoplasmic reticulum (RER) appears in the form of cisternae which are flattened membrane sacs. In ultrathin sections for transmission electron microscopy, they appear as double membrane profiles. As seen here in a portion of a rhizodermal cell of the water plant Limnobium bogotense (a member of the grass family), the RER is extensive. It is involved in the synthesis and storage of specific proteins (hydrolytic enzymes, membrane, storage and secretory proteins), as well as membrane and storage lipids. In plant cells involved with hydrolytic activity, the RER may be found in association with vacuoles.