Thin filament of a muscle (labels) - histology illustration

This is a histology illustration of a thin filament.

Histology illustration courtesy of Rama and modified by ser:Raul654 (Wikimedia Commons). Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".