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.
The 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:.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.