Sac
Part of speech: noun
Definition: A bag or pouch inside a plant or animal that typically contains a fluid.
Theca
Part of speech: noun
Definition: Any external case or sheathHalf of an antherThe twin layers of cells surrounding the basal lamina of an ovarian follicleThe membrane complex enveloping the cells of certain plankton including diatoms and dinoflagellatesThe calcareous wall of a corallite, the exoskeleton of a coral polyp