for ease of insertion and bonding into nuclear slot 28 a of nuclear mounting region 28 b indwelling catheter 32 is relatively stiff and may be formed from polyurethane or polyethylene material not shown and may include a braided or helically wound wire reinforcing layer not shown to resist kinking in a preferred embodiment indwelling catheter 32 is formed by extruding a plurality of layers not shown including a suitably bondable outer layer not shown into a tubular form a seal plug not shown is inserted into indwelling catheter 32 for obstructing the lumen of indwelling catheter 32 after inflation of nuclear enclosure 24 is complete the seal plug is prevented from being dislodged from the lumen of indwelling catheter 32 by the constriction of the slit like pathway 40 of sealing valve core 28 following retraction of inflation stylus 100 referring to fig1 through 3 and fig1 b through 3c annular enclosing layer 12 has a doughnut configuration with a substantially concave inner margin 16 and a substantially convex outer margin 18 providing for inward folding of the concave inner margin 16 forming a substantially u201c c u201d shaped flat band upon deflation of nuclear prosthesis 10 the substantially u201c c u201d shaped flat band configuration of.