AQP4 and Hydrocephalus: Interestingly, we observed that this CD11c+ microglial cell population remained in the periaqueductal area of the AQP4-KO animals for longer and at higher levels than those detected in the WT animals, allowing us to propose that their overexpression during postnatal development in KO mice was necessary to reduce abnormalities of the ependyma and prevent the possible development of hydrocephalus.