Neurospheres can be grown from the cerebrospinal fluid of hydrocephalic HTx rats. The disruption of the ventricular zone (VZ) leads to the abnormal translocation of neural stem cells (NSC) and neural progenitor cells (NPC) into the ventricle[10, 11]. A. Coronal section of hydrocephalic brain stained with haematoxylin-eosin. Cells collected from the cerebrospinal fluid (CSF) of hydrocephalic HTx rats at postnatal day 1 (PN1) were cultured in medium containing 20 ng/ml epidermal growth factor (EGF) for six days. BrdU was added to the culture medium for the last 24 h. B-D. Immunofluorescence of large and small neurospheres with anti-BrdU stain showing proliferative (NSC/NPC) cells. C. High magnification of a small neurosphere. D. High magnification of a large neurosphere. E. After 6 days in vitro neurospheres had an irregular outline, with cells “disrupting” from its periphery (arrows) resembling that of the VZ of the living mutant. DIC, Differential interference contrast microscopy. Scale bars: A 600 μm; B 50 μm; C 5 μm; D, E 10 μm.