Novel bioabsorbable polymeric porous tubes for tissue engineering nerve growth are disclosed. The tubes are made from a bioabsorbable polymeric foam material and have a gradient of pore sizes across the wall thickness of the tubes such that cell growth occurs into the wall of the tubes from the inner surface, while cell growth or entry is not permitted through the outer wall into the tubular wall. The wall is permeable inwardly and outwardly to fluids. A novel method of manufacturing porous nerve tubes is also disclosed.