One optic nerve of an adult mouse was crushed in the orbit. After 8 days, both retinas were explanted onto laminin-coated coverslips. Within 24 h, neurites grew out onto this substrate from explants with prior crush and by 48 h two-thirds of explants had neurites. On polylysine or plain glass, outgrowth was generally not seen until 48 h and this was significantly reduced compared to laminin. Explants without optic nerve crush did not extend neurites until about 5 days later. We suggest that axotomy induces a time-dependent regenerative response in adult mammalian retinal ganglion cells which includes the expression of laminin responsiveness.