Most of the axons in the central nervous system are wrapped in myelin, a substance rich in lipids (fatty substances) and proteins. Like the coating around an electrical wire, myelin insulates and protects the axon and helps speed nerve transmission.
Potato/Semi Round Pearls. Potato pearls are some of the less expensive freshwater pearls to be found on the market, but their look is anything but cheap. You can purchase potato pearls in every color of the rainbow, and craft beautiful one of a kind creations for gifts and your own collection.
The nucleus bead in a beaded cultured pearl is generally a polished sphere made from freshwater mussel shell. Along with a small piece of mantle tissue from another mollusk (donor shell) to serve as a catalyst for the pearl sac, it is surgically implanted into the gonad (reproductive organ) of a saltwater mollusk.