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 outer shell of the long bone is made of cortical bone also known as compact bone. This is covered by a membrane of connective tissue called the periosteum. Beneath the cortical bone layer is a layer of spongy cancellous bone.he long bones are those that are longer than they are wide. They are one of five types of bones: long, short, flat, irregular and sesamoid. Long bones, especially the femur and tibia, are subjected to most of the load during daily activities and they are crucial for skeletal mobility.