[A histomorphometric study of normal iliac trabecular bones. Part II: Age changes and the values of MWT and related parameters].

The Mean Wall Thickness (MWT) of the trabecular packet and other related indices: number of osteocytic lacunae (N-0) and maximum number of birefringent lamellae (N-1) in the packet were measured in 142 normal Japanese subjects (male 55, female 87, mean age 44.8 yrs). MWT was obtained by the equation MWT = 2S/L, where S and L designate area and perimeter, respectively. The MWT, S, and L of the packets all decreased significantly after young adulthood. N-0 and N-1 also decreased significantly with age. In contrast, S/(N-0), which is the measure of the volume of the matrix being formed by a single osteoblast, did not change with age. Therefore, it may be concluded that BMU-leveled bone formation decreases with age probably due to the decreased number of osteoblasts which participate in forming a trabecular packet.