Normal prenatal development of the human parietal bone and interparietal suture.

This study describes the prenatal human parietal bone development and interparietal suture morphology under normal conditions. The human fetal material consisted of 15 normal specimens, derived from spontaneous and therapeutically induced abortions. The study was based upon a radiographic analysis of the calvariae. Special attention was paid to the parietal tuber area, the interparietal (sagittal) suture and the frontal-parietal bone edge. The osseous morphology of these regions showed a well-defined primary ossification center at the tuber region from where bone trabeculae of uniform size and radiopacity radiated. The uniform trabeculae radiate at nearly right angles to the long axis of the sagittal suture. The bony trabeculae radiate uniformly towards the anterior fontanelle where at the peripheral border of the parietal bone radiopaque, transverse ossification corpora were observed. In the small fetuses, these corpora were located anterior to the trabeculae and in the larger fetuses close to the trabeculae. Insight into the morphological pattern in normal suture formation is essential for the further description of pathological suture morphology and for understanding normal and pathological suture development.