GFAP and mucopolysaccharidosis type 3A: While astrocyte reactivity has been demonstrated in the CNS of MPS IIIA mouse models [41,44], zebrafish do not possess parenchymal astrocytes, with immunoreactivity or transgene expression of GFAP (a widely used marker for reactive astrocyte identity in mammalian tissue) restricted to ventricular radial glial-like cells [45,46].