Objectives:The purpose of this study was to determine whether bone elongation rate and bone cell number in the metaphysis of long bones were altered by Cosmos 1129 space flight. An attempt was made to measure the rate of bone elongation directly in the proximal tibial and humeral metaphysis by the use of tetracycline labeling.
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Approach:
The proximal tibial and humeral metaphysis from groups of animals sacrificed at recovery (R-0) and six (R+6) and twenty-nine days (R+29) postflight was measured using quantitative light microscopic techniques. One section of the proximal humerus of each animal was randomly selected. The following parameters were calculated for each band analyzed in the metaphysis: fractional bone and fractional calcified cartilage volumes; osteoblast, osteoprogenitor cell, and osteoclast nucleus numbers; ratios of osteoblast, osteoprogenitor cell, and osteoclast nuclei to surface area of bone; and fractional fatty marrow volume.
Results:
The study demonstrated a reduction in bone and calcified cartilage volume in flight and synchronous animals, in a region of the metaphysis where a maximum of calcified tissues was seen in vivarium controls. This was associated with a decreased number of functional bone cells (osteoblasts and osteoclasts) in both flight and (probably) synchronous groups. It was also clear that the metaphysis had returned to normal by the end of the 29-day recovery period. The fatty marrow volume was increased only in flight groups R-0 and R+6, but was normal in R+29 animals. The decreased amount of bone and calcified cartilage is believed to be the result of a temporarily slowed or arrested production of calcified cartilage as a substrate for bone formation. This would have resulted from slowed bone elongation during flight and synchronous control conditions. Since the synchronous group seemed to show significant changes quite similar to the flight animals, this data indicate that the general stress as well as the flight itself had an effect on the rate of bone elongation.
Jee, W.S.S. et al.: Effects of Spaceflight on Trabecular Bone in Rats. American Journal of Physiology, vol. 244, 1983, pp. R310-R314.
Jee, W.S.S. et al.: Quantitative Analysis of Selected Bone Parameters: Supplement 2: Bone Elongation Rate and Bone Mass in Metaphysis of Long Bones. Final Reports of U.S. Rat Experiments Flown on the Soviet Satellite Cosmos 1129. M.R. Heinrich and K.A. Souza, eds., NASA TM-81289, 1981, pp. 149-175.
Kimmel, D.B. and W.S.S. Jee: A Quantitative Histologic Analysis of the Growing Long Bone Metaphysis. Calcified Tissue International, vol. 32, 1980, pp. 113-122.
Area, Marrow, humerus, bone, rat, Microscopy
Area, Marrow, tibia, bone, rat, Microscopy
Count, Osteoblast, humerus, bone, rat, Histology, microscopy
Count, Osteoprogenitors, humerus, bone, rat, Histology, microscopy
Formation, bone, Humerus, cartilage, tetracycline labeling, fractional calcified cartilage volumes, Calculation
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Formation, bone, Humerus, osteogenesis, tetracycline labeling, Quantitative light microscopic techniques
Formation, bone, Tibia, humerus, cartilage-metaphyseal junction, tetracycline labeling, fractional bone and fractional calcified cartilage volumes, Calculation
Volume, Humerus (fractional), bone, rat, Quantitative light microscopic techniques