The buccal cavity opens into the developing digestive (food) vacuole at the terminal edges of the alveolar sacs that cover the buccal cavity. A plane connecting these edges would roughly describe a tear drop-shaped opening that has been called the cytostome or cell mouth. The cytopharynx (cp) just beyond the buccal cavity encircles the cytostome. The cytopharynx consists of two sides, the left side (shown here) from which 40 or more ribbons of cytopharyngeal microtubules curve over a cytostomal cord. This edge runs along the dorsal side of the quadrulus and borders the terminal margins of the alveolar sacs. Discoidal vesicles are transported along the microtubular ribbons to the left edge of the cytopharynx. TEM taken on 3/25/81 by R. Allen with Hitachi HU11A operating at 75kV. Neg. 5,000X. Bar = 1µm