Formation and maturation of the human sternum. I. Fetal period.

In continuing attempts to develop reliable morphologic, x-ray, and gross criteria for age estimation utilizing the sternum and costal cartilages, it became necessary to study the fetal development of the sternum. While there is a wide variability in the number and configuration of the ossification centers of the developing sternum, several basic developmental patterns emerge. These are illustrated and compared with Ashley's classic work. In general, ossification begins in the manubrium and progresses to the mesosternal (body) segments, developing from rostral to caudal. The more or less final sternal pattern is not found until a number of years after birth. The wide variation in fetal sternal development would seem to preclude its use for satisfactory gestational age estimation; it is clearly less valuable than other morphologic criteria already available. However, an understanding of fetal development does greatly assist in understanding the pre- and postpubertal sternal patterns.