Table 1.

Structural determinants of regenerative activity of two CGSs.

structural parameter required for regenerative activity	skin regenerationa	nerve regenerationb	structural feature hypothetically responsible for contraction blocking
type I collagen/GAG (w/w)	98/2	98/2	ligand identity
residual collagen fibre banding	approximately 5% of native collagen	approximately 5% of native collagen	reduction in recruitment of contractile cells
average molecular weight between cross-links (kDa)	5–15	40–60	controls duration of undegraded scaffold during contraction
average pore diameter (μm)	20–120	5–10	ligand density
pore-channel orientation	random	axial	ligand orientation

^aApproximate levels of structural determinants observed in skin regeneration studies conducted by grafting the scaffold on a full-thickness skin wound (Yannas et al. 1989).

^bApproximate levels of structural determinants observed in peripheral nerve regeneration studies performed by inserting the scaffold inside a nerve conduit (the conduit connected the two stumps of the transected nerve across an experimental gap of defined length) (Chang et al. 1990; Chang & Yannas 1992).