The
endoneurium (also called
endoneurial channel,
endoneurial sheath,
endoneurial tube, or
Henle's sheath) is a layer of delicate
connective tissue around the
myelin sheath of each myelinated
nerve fiber. Its component cells are called
endoneurial cells. The endoneuria with their enclosed nerve fibers are bundled into groups called
nerve fascicles, each fascicle within its own protective sheath called a
perineurium. In sufficiently large nerves multiple fascicles, each with its
blood supply and fatty tissue, may be bundled within yet another sheath, the
epineurium.