Growth and Development of Major Limb Bones from Completed Week Age Fetuses
Fu Mao Wu Xiufen Sun Zhao Department of Histology and Embryology,West China University of Medical Sciences Chengdu 610041
The dynamics and charateristics of the fetal growth in limb long bones were studied in 177 fetuses (92 male, 85 female) with anatomic method. Fetal age ranged from 12 32 complete weeks. Comparisons were made between bones on the left and right sides of the body and between the sexes; no significant differences were noted. The results show that the crown rump length and weight are positively correlated with the length of limb long bone, and the regression equations have been obtained. The lengths of the major limb bones increase with fetal age, but the rates of growth are different during the different periods of fetal life. The lengths of cartilage in limb long bones increase with fetal age. The ratios of cartilaginous length vs maximum length decrease with the fetal age. These indicate that the higher the cartilaginous percentage is. the younger the fetal age is. At 12th week the maximum lengths of lower limbs are longer than those of upper limbs. In terms of the averages of ossification shaft lengths, the femur overtakes humerus at 15th week; the fibula overtakes radius at 14th week; and the tibia overtakes ulna at 19th week. The ulna and tibia follow similar growth patterns.