The infant Apert skull.

During early infancy, the Apert skull is literally wide open. It is characterized by a gaping midline calvarial defect that extends almost from the root of the nose through the metopic suture area, anterior fontanelle, and sagittal suture area to a widely patent posterior fontanelle. Only the coronal suture area is prematurely fused. During the first 2 to 4 years of life, bony islands that have formed in the midline enlarge and coalesce, obliterating the midline calvarial defect without any evidence of suture formation.