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.he basic unit of Compact Bone is an  osteon , which is also known as a  Haversian System . Each Haversian System (unit) has a cylindrical structure that consists of four parts: 1  A central tube called a Haversian Canal, which contains blood vessels and nerves. 2  The Haversian Canal is surrounded by alternate layers of: