MULTIVARIATE-ANALYSIS OF LIMB LONG-BONE GROWTH DURING THE HUMAN PRENATAL PERIOD

Prenatal development of the human limb bones (humerus, ulna, radius, f emur, tibia, fibula) was studied. Cross-sectional data, consisting of 21 anthropometric measures of these bones mere collected from 122 Japa nese fetuses between the gestational ages of 18 and 40 weeks. Principa l component analysis was applied to the data to provide multivariate a ssessments of morphological patterning among the variables. Three orth ogonal components that accounted for 94.2% of the overall sample varia tion were extracted. The first component accounted for 88.2% of the va riation and represented an axis of overall body size that was dependen t on gestational age. The second and third components both reflected a trend in shape involving the cartilaginous parts of the humerus and f emur. The findings indicated that different growth factors existed bet ween the ossified and cartilaginous parts of fetal long bones. Multiva riate allometric coefficients were extracted from the first principal component. The variables that were related to the construction of the articulate showed positive allometry, and the central widths of the di aphysis showed negative allometry compared with total size. In prenata l skeleton, certain shape changes are functionally linked to and requi red by changes in body size. A comparison among the coefficients of lo ng bone length revealed that lower limb bones grew faster than upper l imb bones during the period under study here. Allometric coefficients were equivalent among bones within a limb, whereas homologous bones in the upper and lower limb grew at different rates.