Figure 1.
Sites of Ca2+ release in skeletal and cardiac muscle. (A and B) Transversal and longitudinal sections of a skeletal muscle triad junction. TC, terminal cisternae. (C) Transversal section of junctions in a cardiac myocyte, between a larger transverse tubule (TT) and very narrow SR cisternae. (D) Protein-filled vesicles (presumably dilated cisternae) in cardiomyocytes of mouse overexpressing calsequestrin 2, to demonstrate that the volume differences are largely determined by the quantity of calsequestrin. A and B show unpublished images by C. Franzini-Armstrong. C and D show images modified from Jones et al. (1998) with permission from The American Society for Clinical Investigation, Inc.
