01 October 2021. Vol.12 No.7
ISF drainage routes in juvenile (≤P30 days) and adult rats. In juvenile rats (≤P30 days), the brain has not been fully myelinated, the oligodendrocytes are small, myelin sheaths are thin, and many axons are nonmyelinated. The interstitial fluid (ISF) was traced from the caudate nucleus (Cn) drained to the ipsilateral cortex along myelin fiber tracts and can communicate with the ISF in the thalamus (Tha) in the opposite direction. After P40, ISF drainage in Cn became regionalized; the movement of ISF to the adjacent thalamus was completely impeded by a barrier structure composed of compact myelin (yellow arrow). The oligodendrocytes in adult rats were more developed than the juvenile rats (blue arrow).