Histological study of the developing human femur

The development of the long bones at various gestational ages in the fetus has always been a subject of interest for many clinicians. Some morphometric parameters such as length, etc., are considered standard parameters for evaluation of the gestational age of the fetus. However, not much emphasis is laid upon morphometric parameters to assess the histological changes in these age groups. Therefore, the present study was undertaken to determine the histological changes occurring in a developing bone. 30 fetuses sent to the Dept. of Anatomy for routine fetal autopsy by the Dept. of Obstetrics and Gynaecology were selected for the microscopic study of the femur. Left femora were extracted, and transverse and longitudinal sections were taken and stained with hematoxylin and eosin. The epiphysis of the growing bone exhibited the formation and proliferation of different zones in different age groups. The formation and distribution of distinct cartilage canals has been evidenced as early as 13 weeks of gestation in the growing epiphysis. The appearance of a secondary centre of ossification in the distal femoral epiphysis was observed as early as 28 weeks. The diaphysis showed the formation of a cancellous bone with increasing trabeculae proliferating more on one side of the shaft. The above observations are discussed in the light of available literature.