Histomorphology and its experimental alteration of coronal suture in mice.

The normal histomorphology of the coronal suture in mice was observed, and sutural function was then examined by two types of incision of the parietal bone; one was a -shaped incision made on the parietal bone, leaving the anterior margin of the bone fragment in contact with the coronal suture alone for suture release from external demands, and the other was a ||-shaped incision on the parietal bone intersecting at right angles to the sutural orientation, with the suture left under external demands.From the observation of the sutural interdigitation in the outer and the inner surfaces of the calvaria, the former was intensely interdigitated, and the latter slightly interdigitated. In the sutural sagittal section, the lamina interna of the parietal bone interdigitated between the lamina externa and interna of the frontal bone. Nevertheless, the lamina externa of the parietal bone was abnormally developed. The collagen fiber bundles were oriented in the anteriorposterior direction in the upper half of the suture and were obscure in the lower half. In the -shaped incision, the suture was remodelled, and the orientation of collagen fiber bundles throughout the suture was obscure. In the ||-shaped incision, in contrast, the sutural histomorphology remained near to normal.These findings suggest that the coronal suture acts as an articulation; the upper half of the suture having mobility while the lower half acts as a fulcrum.