theca

noun8

1. •
   Any of several external cases or sheaths.
2. •
   The pollen-producing organ usually found in pairs and forming an anther.
3. •
   The theca folliculi: the twin layers of cells surrounding the basal lamina of an ovarian follicle.
4. •
   The thecal sac: the portion of the dura mater that surrounds the spinal cord and the cauda equina.
5. •
   The membrane complex enveloping the cells of certain plankton including diatoms and dinoflagellates.
6. •
   The calcareous wall of a corallite, the exoskeleton of a coral polyp.
7. •
   A sporangium: a spore case.
8. •
   A case for the corporal cloth used in the Eucharist.