VAN 211: Veterinary Histology and Embryology (2+2)

COMPACT BONE

• This is composed of numerous systems of concentrically arranged bony lamellae, around a central canal, the Haversian canal, which run longitudinally and encloses blood vessels.
• Each concentric system is known as a Haversian system or Osteone.

• Haversian canals of adjacent systems are inter connected by transverse channels and volkmann’s canals connect haversian canals with periosteal and endosteal surfaces.
• In a cross section of the bone, the Haversian canals are seen to be surrounded by a varying number (8 to 15) of concentric lamellae. These concentric lamellae and the central canal constitute a Haversian system or Osteone. In the periphery, the lamellae are not concentric but run parallel with the surface and form a relatively thin outer layer of the bone, the outer circumferential or general lamellae. Similarly arranged inner circumferential lamellae separate the Haversian systems from the marrow cavity.
•  Finally, the intervals between the Haversian lamellae are occupied by more irregular layers of bone which constitute the intertitial lamellae. Adjacent lamellar systems are as a rule sharply delimited from each other by a dark staining thin layer of modified matrix (cement membrane, cement line).