ribonucleic acid, RNA (noun). (biochemistry) a long linear polymer of nucleotides found in the nucleus but mainly in the cytoplasm of a cell where it is associated with microsomes; it transmits genetic information from DNA to the cytoplasm and controls certain chemical processes in the cell.
Osteocytes â mature osteoblasts. Osteoclasts â bone-destroying cells. Compact bone A structural unit of a compact bone is called an osteon (or Haversian system). Osteon â cylindrical structure oriented parallel to bone's long axis.Osteon consists of hollow tubes, one inside the other, called lamella.steocytes â mature osteoblasts. Osteoclasts â bone-destroying cells. Compact bone A structural unit of a compact bone is called an osteon (or Haversian system). Osteon â cylindrical structure oriented parallel to bone's long axis.Osteon consists of hollow tubes, one inside the other, called lamella.
2.2 The Structure of Spongy Bone Spongy Bone does not include osteons (the basic unit/s of Compact Bone-see above). Instead, spongy bone consists of an irregular lattice of thin columns of bone called trabeculae (literally little beams), which contain lamellae, osteocytes, lacunae and canaliculi.here are two main types of bone tissue, compact bone and spongy bone. Individual bones in the body can be formed from both of these types of bone tissue. The diagram on the right shows the physical structure of a typical  long bone .