n. (context cytology English) A network of membranes within the cytoplasm of cells, where proteins and lipids are synthesized.
The endoplasmic reticulum (ER) is a type of organelle in the eukaryotic cells that forms an interconnected network of flattened, membrane-enclosed sacs or tube-like structures known as cisternae. The membranes of the ER are continuous with the outer nuclear membrane. Endoplasmic reticulum occurs in most types of eukaryotic cells, including Giardia, but is absent from red blood cells and spermatozoa. There are two types of endoplasmic reticulum: rough and smooth. The outer ( cytosolic) face of the rough endoplasmic reticulum is studded with ribosomes that are the sites of protein synthesis. The rough endoplasmic reticulum is especially prominent in cells such as hepatocytes. The smooth endoplasmic reticulum lacks ribosomes and functions in lipid manufacture and metabolism, the production of steroid hormones, and detoxification. The smooth ER is especially abundant in mammalian liver and gonad cells. The lacy membranes of the endoplasmic reticulum were first seen in 1945 using electron microscopy.
Usage examples of "endoplasmic reticulum".
In the complex cell that was the Authority, he was no more than endoplasmic reticulum, a conduit between the nucleus that was the Colligatarch and the surging protoplasmic mass of mankind.
The micrograph showed the bug, with its bacteria-like lack of a nucleus, its amoeba-like pseudopods and irregular cellular borders, and its just-plain-weird ribosome clusters and endoplasmic reticulum, plus some things not even Marlowe could identify.