Question

why endoplasmic reticulum called as cytoskeleton

Answer 1

The general structure of theendoplasmic reticulum is a network of membranes called cisternae. These sac-like structures are held together by the cytoskeleton. The phospholipid membrane encloses the cisternal space (or lumen), which is continuous with the perinuclear space but separate from the cytosol.

Answer 2

because it form net like structure thus provide mechanical support to cell