- Refers to a dark line between adjacent I-bands under a microscope. This area is the border, or walls of the "sarcomere", and is comprised of connectin protein that acts as an anchor for the actin filaments.
Example, a sacromere (the smallest functional unit of a muscle cell) may be defined as a segment of a myofibrile between two Z disks.
- Saladin, K. (2014). Anatomy & physiology: The unity of form and function. McGraw-Hill Higher Education, New York. ISBN: 9780073403717