The study focussed on the mice at 11 days after birth (P11), given that in the AQP4−/−(AQP4-KO/CD1) mice used by Feng et al. [30], the sporadic hydrocephalus phenotype was observed starting at this stage of development and because the highest AQP4 mRNA expression was observed in the periaqueductal zone of WT mice at that age, as shown in the present work. This evidence concerns the gene AQP4 and Hydrocephalus.