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Crosstalk between astroglia and nerve fiber outgrowth might be an underlying mechanism for regeneration of nerve fibers and can be used in treatment of neurodegenerative diseases. This crosstalk might occur through the integrin-associated protein (CD47 in mouse or OX101 in rat), which serves as a ligand for signal regulatory protein-α (Sirpα) (P84/SHPS-1 in mouse or OX41 in rat), and as a receptor for thrombospondin (TSP). In the present study the localization of OX101 was assessed in organotypic tissue cultures from ventral mesencephalon (VM) of embryonic day (E) 14 rat fetuses, and its presence in astrocytes was observed. Thereafter, the effect of OX101 was blocked in E14 VM cultures by treatment with OX101 antibodies. A robust tyrosine hydroxylase (TH)- positive nerve fiber outgrowth was observed using immuohistochemistry. In addition, the neurons had migrated from the tissue slice. This result was in parallel with results achieved from E14 cultures of CD47 knockout mice, in which TH–positive nerve fiber growth was robust and independent of the presence of astrocytes, whilst in wildtype cultures nerve fibers were restricted to the astrocytes. Thus, these data demonstrate that CD47/OX101 can be an important molecule, which normally is produced by astrocytes and in its absence, the astrocytes become more permissive for nerve fiber growth.