Myelinated axons are the most prominent structures in peripheral nerve bundles (PNBs). Because of the quality of preservation, you can get a sense of the relation between the diameters of the axons (clear) and the thickness of the myelin sheaths (dark blue), particularly in the transverse sections. There are many transversely sectioned myelinated axons in this image. PNBs are tortuous or wavy in structure, because they undergo stretch with body movements. If they ran straight and were taut, they could break with mechanical stress such as over-stretching. At the edge of the PNB, at the left, is a darker layer of perineurial cells and a lighter layer of epineurial connective tissue, which both serve a protective function.