obsolete endoplasmic reticulum part (obsolete GO:0044432)
ER component
exact
OBSOLETE. Any constituent part of the endoplasmic reticulum, the irregular network of unit membranes, visible only by electron microscopy, that occurs in the cytoplasm of many eukaryotic cells. The membranes form a complex meshwork of tubular channels, which are often expanded into slitlike cavities called cisternae.