Of note, rag2-/- immunodeficient mice on a C3h background were generally used as recipients for these experiments, although rag1-/- immunodeficient mice (on a C57/Bl6 background) were used for vision-dependent behavioral tests, since the C3h background of the rag2 mice is a visually impaired strain; we observed no difference in xenograft acceptance, cell dispersal or differentiation patterns between these two hosts. In that regard, we found no evidence of microglial activation in the xenografted mice, whether in rag1- or rag2-null hosts, reflecting both their neonatal engraftment and immunodeficient backgrounds (Figs. S1B-F)
