Skeletal muscle cell types include: very large multinuclear muscle fiber cells; small endothelial cells that line the inside of capillary blood vessels; small fibro-adipogenic progenitor cells (FAPs) which are muscle-fiber-adjacent multipotent mesenchymal stem cells that under different conditions can differentiate into adipocytes, fibroblasts or osteocytes. Also shown are pericytes situated on the outer surface of blood capillaries, where they interact with the underlying endothelial cells. In addition, satellite cells are shown that can fuse with muscle fibers and contribute new myonuclei to muscle fibers, grow into new myocytes, or support focal membrane damage repair.[1]

U.S. Air Force Maj Jonathan Forbes, 455th Expeditionary Medical Operations Squadron neurosurgeon looks through loupes as he performs brain surgery at the Craig Joint Theater Hospital, Bagram Air Field, Afghanistan, Oct. 10, 2014. The loupes allow Forbes to see the surgery at a two times magnification. Forbes removed an 8-centimeter tumor during the five-hour surgery. Forbes is deployed from Travis Air Force Base, Calif., and is a native of New Martinsville, W.Va. (U.S. Air Force photo by Staff Sgt. Miguel Lara III/Released) Unit: 455th Air Expeditionary Wing