Morphological and morphometric analysis of the hippocampus in Wistar rats with experimental hydrocephalus.

The present study aims at better establishing the alterations caused by the usual enlargement of brain ventricles in this structure. Hydrocephalus was induced in 7-day-old Wistar rats by the injection of kaolin into the cisterna magna. Morphological studies were performed on the hippocampus 7, 14 and 21 days after injection. The total number of neurons in each hippocampus subarea as well as that of pyknotic neurons were counted. Then we calculated the pyknotic index (PI) by hippocampal subarea, taking into account the level of ventricular dilatation and time of induction of hydrocephalus. PI was statistically larger in the CA1 subarea of the experimental group after 1 week of hydrocephalus induction as compared to the corresponding control as well as in animals that had developed mild hydrocephalus in groups G1, G2 and G3. Hydrocephalus caused morphological alterations in the hippocampus, leading to important changes in its shape.