[Early bone and cartilage histogenesis in embryonic Japanese quails in the conditions of microgravity].

The article presents the results of a comparative histological investigation of skeletal bones genesis in Japanese quail embryos developed in the spaceflight microgravity (space group) and laboratory (control group). Total preparations of 4-day-old embryos from both groups demonstrated clearly that the cartilaginous anlage of the femoral bone had central, dyaphisial, 2 epiphysial and 2 proliferation zones. By day 7 of embryogenesis, cartilaginous anlages had grown in size in both groups due to intensive chondrocytes multiplication and gain in the intercellular substance mass. Tibial cuff in space embryos measured half and femoral cuff was 2.3 times smaller in comparison with these parameters in the control group. In addition, intensity of chondrocyte multiplication was reduced Histological profiles of the femur and tibia in 10-day old embryos of the control pointed to enhancement of osteogenesis. The metaphysis zone contained distinct mitosis figures on different stages of division. Bone deposition could be seen below the peristoma. The osteogenesis cuff spread up to the femoral anlage metaphysis; cartilage was calcined. Space embryos display retard osteogenesis. There were ingrown blood vessels in the region of cartilage destruction; however, vessels grown in the periosteum were less in number as compared with the laboratory control. Also, the perichondral ossification layer was considerably thinner, whereas the osseous cuff was 1.3 and 1.45 times shorter in the femur and tibia, respectively. To sum up, the histological investigation of bones from 4-, 7- and 10- day old Japanese quail embryos demonstrated retardation of osteogenesis in the conditions of microgravity.