Tanycytic barrier

There are other aspects of barrier function that also change with development. The tanycytic barrier between the median eminence and the arcuate nucleus develops after birth in the rodent (Peruzzo et al 2000). This means the arcuate nucleus is very vulnerable to circulating neurotoxins during the neonatal period. For example, monosodium glutamate destroys the arcuate nucleus with resulting obesity when given intravenously to a neonate, but not an adult. The epithelial cells, which line the ventricles of the brain, have tight junctions even over non-CVO sites in neonates, but not adults. Thus, neonates have a CSF-brain barrier, which limits the diffusion of substances between brain tissue and CSF... 

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