Relation of age and cerebral ventricle size to central canal in man. Morphological analysis.

The central canal of the spinal cord in man with and without hydrocephalus was studied histologically. The lumen was patent in most patients in the first two decades of life. Cells lining the canal in the prenatal and newborn state and in the first decade of life were predominantly pseudostratified ciliated epithelium. In the second decade, the epithelium became simple columnar or cuboidal. The central canal closed in most cases after the age of 20 years, secondary to proliferation of ependymal cells and astrocytes. Mechanisms whereby the number of glial cells increase are considered. The canal was closed in all adults with normal ventricular size, and in 94% of persons with various degrees of hydrocephalus. In the remaining 6% of cases with hydrocephalus, the lining of the canal resembled that seen in the first two decades, and could have acted as a pathway of cerebrospinal fluid (CSF) absorption. Three cases of severe hydrocephalus in the first two decades of life were encountered; the central canal was patent in one, and occluded in two. Based on these data, the canal was not a significant pathway of CSF absorption in most instances of hydrocephalus and in persons with dilated ventricles who were older than 20 years of age.