part of endoplasmic reticulum perinuclear region of cytoplasm perinuclear endoplasmic reticulum 2011-04-12T10:51:05Z perinuclear ER GO:0097038 The portion of endoplasmic reticulum, the intracellular network of tubules and cisternae, that occurs near the nucleus. The lumen of the perinuclear endoplasmic reticulum is contiguous with the nuclear envelope lumen (also called perinuclear space), the region between the inner and outer nuclear membranes. pr cellular_component cellular anatomical structure