A treated surface of a device (10) for implantation or for application as a wound dressing, comprises an array of plasma-activated hydrophilic cell-adhesive areas (18) having the ability to reduce fibrous reaction, is in the form of an array of islets of activation. Each islet of activation (18) has a length which is less than 6 &mum, a width which is less than 2 &mum and the distance between islets is preferably from 4 &mum to 6 &mum. The islets of activation (18) are surrounded by non-activated, non-adhesive, hydrophobic areas.
