theca

noun (plural thecae /ˈTHēsē/)

• a receptacle, sheath, or cell enclosing an organ, part, or structure, in particular.
• Anatomy the loose sheath enclosing the spinal cord.
• Zoology a cuplike or tubular structure containing a coral polyp.
• Botany either of the lobes of an anther, each containing two pollen sacs.
• (also theca folliculi /fəˈlikyəˌlī/) Anatomy the outer layer of cells of a Graafian follicle.