Abstract
A quantitative study of the volume and cellular constitution of the bone marrow was carried out in 10 guinea pigs of approximately 400 Gm. body weight, which had been born and reared at a simulated altitude of 14,000 feet, and in 10 normal controls.
The hemopoietic marrow of the experimental group was more cellular and showed a marked increase in the number of erythroid cells per unit volume. No significant changes were demonstrated in the absolute counts of other cells, but fat vacuoles appeared less numerous. The fatty (yellow) marrow occupied its normal centrifugal position in the skeletons of both groups.
No absolute increase in the volume of bone marrow was detected in the experimental group, but the red marrow volume formed a significantly greater proportion both of the volume of the skeleton containing it and of the total marrow volume.
It was concluded that the marrow of the hypoxic animals had a total population of erythroid cells about 40 to 50 per cent greater than normal; this increase was largely accommodated by closer packing of cells in the red marrow.
