“…The evidence to support this idea comes from a variety of circumstantial observations. For instance, in cell culture, laminin has been shown to be the most effective of all substrates so far tested in supporting neurite outgrowth and elongation of neurons from both the CNS and PNS ( Baron-van Evercooren et al, 1982;Manthorpe et al, 1983;Rogers et al, 1983;Edgar et al, 1984;Faivre-Bauman et al, 1984;Liesi et aI., 1984a,b;Smallheiser et al, 1984;Calof & Reichardt, 1985). It is transiently expressed in early developing fibre tracts in the CNS in a form that is particulate and not associated with basal laminae (Cohen et al, 1987;Letourneau et al, 1988 but see Sosale et aI., 1988) and permanently present in regions of the CNS in which axons are added continuously throughout adult life, such as the rat olfactory system (Liesi, 1985b) and the goldfish optic nerve (Hopkins et al, 1985).…”