Neuropathology of congenital hydrocephalus in the SUMS/NP mouse.

The neuropathology of congenital hydrocephalus in SUMS/NP mice was investigated in this study. Hydrocephalus occurred with an incidence of 16.5% and was evident in the form of an enlarged head soon after birth. The condition was progressive; affected mice gradually became noticeably smaller than normals, acquired functional disturbances and died before ever breeding. Hydrocephalic mice exhibited enormous dilatation of the lateral ventricles, thinning of the cortex and compression and distortion of the diencephalon and striatum. Examination of the midbrain in these animals revealed that the proximal cerebral aqueduct was diminished in size, occluded or absent. Evidence of its anomalous development was seen as early as day 15 of foetal development. This is in substantial agreement with previous reports on this strain. Although the mechanism by which this occurs is still unknown, abnormal development of the adjoining diencephalon and/or rostral midbrain is likely to be involved.