D, A colloid cyst that obstructs the foramen of Monro is being aspirated with a needle. E, A colloid cyst that obstructs the foramen of Monro has been exposed by opening the choroidal fissure along the attachment of the choroid plexus to the fornix. The internal cerebral veins and medial posterior choroidal arteries are exposed behind the foramen of Monro. The cyst’s contents are being removed with a suction. F, The final remnant of the attachment of the cyst to the choroid plexus is being coagulated. G, The column of the fornix has been divided to enlarge the foramen of Monro and the semigelatinous material within the cyst is being removed using a cup forceps and suction. (Images courtesy of AL Rhoton, Jr.)