1991 Volume 2 Pages 59-63
The process of development of the mid-diaphysis of the third metacarpal bone (Mc III) in equine fetuses between 195 and 338 days of gestation was examined morphologically. With increased fetal age, the cortical bone composed of primary spongiosa had compact bone consisting of primary osteons. This produced an increase in the outer circumference, the percentage of cortical bone relative to cross-sectional area, and the bone mineral content at the mid-diaphysis of this bone. It was considered that such developmental changes are adequate for coping with weight-bearing stress after birth. Features of remodeling from primary to secondary osteons were not recognized, and therefore these are thought to arise due to mechanical stress on the bone after birth.
