The structural and functional pattern of vascular bed of the osteochondral junction in femoral heads of mature rabbits

Light and electron microscopical study of osteochondral junction (OCHJ) was carried out in three mature rabbits. The mineralized extracellular mat­ rix (MEM) of the calcified layer of articular cartilage is firmlyjoined with the osseous tissue of bone ends. The firm connection of both components is based on a system of arciform processus of MEM dipped into the subchondral bone. On the other hand, vascular channels penetrate from subchond­ ral bone into the MEM. Vascular channels are encapsulated by a thin mantle of osseous tissue. The terminal vascular net originating in bone marrow and dipped into the MEM of OCHJ is formed by blood sinusoids. The perisinusoidal cleft is on average 20-30 ^m wide and its loose connective tis­ sue is in close contact with extracellular matrix. The structural arrangement of the terminal vascular bed of MEM speaks in favor of a subchondral so­ lute supply to the hyaline joint cartilage. Findings obtained also support the idea of participation of OCHJ in remodeling of articular bone ends in mature age. The loose perisinusoidal and perivascular connective tissue is the source of differentiation of osteogenic cells which take part in the process of endochondral ossification needed for bone remodeling. The predominant parts of the surface of lacunae excavated by vascular channels in MEM of OCHJ are lined by a thin osseous lay­ er separating MEM from the perisinusoidal loose connective tissue. The osseous mantle is considered to be a product of bone neoformation but, on the other hand, a barrier preventing the discoordination of endochondral ossification in the course of bone end remodeling.

Keywords: osteochondral junction, adult rabbit hip, fine structure, role of vascular network.