Spreading throughout the cytoplasm, extending from
the cell membrane to the membranes of the nucleus is a network of membranes that
form channels, tubes, and flattened sacs; this network is named the endoplasmic
reticulum. One function of the endoplasmic reticulum is the movement of
materials throughout the cytoplasm and to the plasma membrane. The endoplasmic
reticulum has other important functions related to the synthesis of materials
and their packaging and distribution to sites needed.
