endoplasmic reticulum

reticulum /re·tic·u·lum/ (rĕ-tik´u-lum) pl. retic´ula   [L.]

1. a small network, especially a protoplasmic network in cells.

2. reticular tissue.

---

endoplasmic reticulum  an ultramicroscopic organelle of nearly all higher plant and animal cells, consisting of a system of membrane-bound cavities in the cytoplasm; occurring in two types, rough-surfaced (granular r.), bearing large numbers of ribosomes on its outer surface, and smooth-surfaced (agranular r.) .

sarcoplasmic reticulum  a form of agranular reticulum in the sarcoplasm of striated muscle, comprising a system of smooth-surfaced tubules surrounding each myofibril.

stellate reticulum  the soft, middle part of the enamel organ of a developing tooth.

---

endoplasmic reticulum

n. Abbr. ER

The membrane network in cytoplasm that is composed of tubules or cisternae. Some membranes carry ribosomes on their surfaces while others are smooth.

---

endoplasmic reticulum

[-plaz′mik]

Etymology: Gk, endon + plassein, to mold

an extensive network of membrane-enclosed tubules in the cytoplasm of cells. The structure functions in the synthesis of proteins and lipids and in the transport of these metabolites within the cell.

---

endoplasmic reticulum (ER),

n an extensive network of membrane-enclosed tubules in the cytoplasm of a cell.