Restricted Pax3 Deletion within the Neural Tube Results in Congenital Hydrocephalus.
The genetic polydactyly/arhinencephaly mouse, Pdn/Pdn, exhibits severe polydactyly both in the fore- and hindlimbs, hydrocephalus, and agenesis of the olfactory bulbs, corpus callosum, and anterior commissure. The mechanism of hydrocephalus manifestation in Pdn/Pdn was investigated in the present study. Ink was injected into the left lateral ventricle in the Pdn/Pdn and +/+ newborn mice. After incubation at 32 degrees C for different time intervals, the heads were fixed in Bouin's solution and were subsequently decalcified in 0.5 mol/L of EDTA solution, paraffin sectioned, and stained with hematoxylin and eosin. Ink spread into the 3rd and right lateral ventricles and flowed to the 4th ventricle and Magendie's foramen rapidly in Pdn/Pdn mice. This rapid spread was due to the dilatation of the interventricular foramen and that the lateral ventricle was directly connected with enlarged 3rd ventricle in Pdn/Pdn. In spite of the rapid spread of ink in the cerebrospinal fluid pathway, ink was not observed in the subarachnoid space around the superior sagittal sinus at 3.5 or 10 hours in Pdn/Pdn mice. The superior sagittal sinus was narrower in Pdn/Pdn than in +/+, and the arachnoid villi were not observed in Pdn/Pdn. From these observations, we suggested that absorption of cerebrospinal fluid from the arachnoid villi in the superior sagittal sinus stagnated and that stagnation of the fluid in the ventricles was the cause of hydrocephalus in Pdn/Pdn mice.