Pathological growth of skull--radiological fine structure in experimental animals

The skulls of 55 mice (strain C57 Black) were studied radiologically at various ages. In the mouse, craniocaudal growth of the skull takes place exclusively within two synchondroses. Longitudinal growth is completed at 50 to 60 days of life and it is dependent on the pressure developed by the growing brain. In strain C57 Black congenital hydrocephalus occurs with an incidence of approximately 8%, causing a characteristic deformity of the skull. Hydrocephalus developing after 30 days of age causes deformity restricted to the calvarium. The base of the skull remains unchanged and may not be distinguished from that of normal individuals of the same age. Abnormal lateral growth of the base of the skull may be observed if hydrocephalus develops in the young mouse: At 25 days pp. the syndesmosis between ospetrosum and the adjacent bones is not yet solidified. Consequently, the ossa petrosa may yield to the increased intracranial pressure. The result is a measurable widening of the distance between the tips of the ossa petrosa. A radiological method is described, permitting high resolution of minute details of the skull of small experimental animals.