A high pressure closed gland unitized seal assembly for sealing against a connector pin in a box and pin seal used in a sub-sea riser joint assembly. The high pressure closed gland unitized seal assembly includes an elastomeric seal body having an inner diameter end and an outer diameter end formed of an elastomeric material having a first modulus of elasticity. The inner diameter end of the seal body includes two diametrically opposed axially outward base portions and an axially inward sealing portion. Integrated with the elastomeric material at the base portions of the inner diameter end of the seal body are a pair of diametrically opposed anti-extrusion rings having a modulus of elasticity that is higher than the modulus of elasticity of the elastomeric material so as to prevent the extrusion of the elastomeric seal body. The anti-extrusion rings are disposed between the elastomeric seal body and tightly wound coil springs.