Micromorphometric characteristics of osteons in compact bone of growing tibiae of human fetuses.

A micromorphometric study of compact bone from 150 tibiae of human fetuses of 6, 7-8 and 9 months of gestation was performed. The following variables were determined: number of Haversian canals per mm2, distance between adjacent Haversian canals, mean diameter of Haversian canals, volume density of the Haversian canals, and volume density of developing osteons. In the earlier periods of intrauterine development the compact bone displays a high volume density of osteons, a few wide bone lamellae, wide Haversian canals with high relative volume and density, and a small thickness of the bone between the canals. Late in gestation, the bone contains osteons with many lamellae, and small relative volume density. Haversian canals are narrow, comparatively sparse, with low volume density and considerable thickness of the intercanal tissue layer. The differences between late and mid-gestation bone tissue are statistically significant.