What are the spherical or tube-like membrane structures that enclose the contents of the endoplasmic reticulum, separating them from the cytoplasm, known as?

Explanation

The endoplasmic reticulum contains membrane-bound compartments called cisternae, which are sac-like or tubular structures that isolate its internal material from the cytoplasm. Cytosol refers to the fluid portion of the cytoplasm, polysomes are groups of ribosomes, and cristae are folds found in mitochondria.