SUBSURFACE CISTERNS AND THEIR RELATIONSHIP TO THE NEURONAL PLASMA MEMBRANE

TLDR

Subsurface cisterns are large, flattened, membrane‑bounded vesicles closely apposed to the inner plasma membrane of neurons, present in many vertebrate and invertebrate neurons but absent from supporting cells, with sheet‑like morphology (luminal depth <100 Å, breadth up to several µm) separated by a 50–80 Å light zone that may contain a faint intermediate line, and similar agranular cisterns distinct from ER and Golgi also occur deep in neuronal cytoplasm. The study proposes that the close apposition of subsurface cisterns to the plasma membrane may alter membrane properties and discusses the potential significance of SSCs for neuronal electrophysiology and metabolism. The patches of neuronal plasmalemma associated with subsurface cisterns may therefore have special properties because of this association, resulting in a non‑uniform neuronal surface.

Abstract

Subsurface cisterns (SSC's) are large, flattened, membrane-limited vesicles which are very closely apposed to the inner aspect of the plasma membranes of nerve cell bodies and the proximal parts of their processes. They occur in a variety of vertebrate and invertebrate neurons of both the peripheral and central nervous systems, but not in the surrounding supporting cells. SSC's are sheet-like in configuration, having a luminal depth which may be less than 100 A and a breadth which may be as much as several microns. They are separated from the plasmalemma by a light zone of approximately 50 to 80 A which sometimes contains a faint intermediate line. Flattened, agranular cisterns resembling SSC's, but structurally distinct from both typical granular endoplasmic reticulum (ER) and from Golgi membranes, also occur deep in the cytoplasm of neurons. It is suggested that membranes which are closely apposed may interact, resulting in alterations in their respective properties. The patches of neuronal plasmalemma associated with subsurface cisterns may, therefore, have special properties because of this association, resulting in a non-uniform neuronal surface. The possible significance of SSC's in relation to neuronal electrophysiology and metabolism is discussed.