sarcoplasmic reticulum
A fine reticular network of membrane-limited elements that pervades the sarcoplasm of a muscle cell; continuous over large portions of the cell and with the nuclear envelope; that part of the endoplasmic reticulum specialized for calcium release, uptake and storage.
GO:0005783
endoplasmic reticulum
is_a
GO:0016528
sarcoplasm
part_of