Therefore, the idea that specific sections of retrograde memory are independent of anterograde is supported. Diastolic inflation increases blood flow to the coronary arteries via retrograde flow. Metamorphism is further divided into prograde and retrograde metamorphism. Surgery to correct benign prostatic hyperplasia may destroy these ducts resulting in retrograde ejaculation. Irregular moons with retrograde orbits are shown in dark grey. Triton is the only large satellite with a retrograde orbit. The irregular satellites begin with wide range of inclinations including prograde, retrograde, and perpendicular orbits. Uranus rotates, which is retrograde to the Sun. The prograde jets are generally more powerful than the retrograde jets. The lymphatic vessels follow the arteries in a retrograde fashion. Only a few dozen asteroids in retrograde orbits are known. Astrological ages proceed in the opposite direction ("retrograde" in astronomy). The integrity of the urethra can be determined by a procedure known as retrograde urethrogram. This has been suggested as an explanation for the preponderance of retrograde moons around Jupiter. In comparison, there are over 2,000 comets with retrograde orbits.