Definition of theca in English:



  • 1A receptacle, sheath, or cell enclosing an organ, part, or structure, in particular.

    1. 1.1Anatomy The loose sheath enclosing the spinal cord.
      • ‘The theca contains the cauda equina or nerve roots.’
      • ‘The vertebral foramen houses the theca and spinal nerves.’
    2. 1.2Zoology A cuplike or tubular structure containing a coral polyp.
      • ‘It is notable that both specimens also display asymmetry in the overall structure of their thecae.’
      • ‘Calices and thecae are commonly intact, but typically lack feeding appendages.’
      • ‘Despite its good preservation, this single specimen did not show all aspects of the theca.’
      • ‘The theca around the column is smooth, sometimes with weak longitudinal muscles.’
      • ‘In the ‘echinoderm’ reconstruction, the theca lies with the convex side upwards and the appendage is interpreted as an anterior feeding arm.’
    3. 1.3Botany Either of the lobes of an anther, each containing two pollen sacs.
      • ‘As pollinators removed pollen from the thecae, their walls collapsed and the anthers curled down gradually.’
      • ‘Stamens are didynamous, but the yellow anthers occur close together, with their divergent thecae spreading to the outside.’
      • ‘The percentage of thecae that dehisced longitudinally varied greatly among rice varieties.’
      • ‘At this stage, at least one theca is already opened, and pollinators are attracted to the flowers.’
      • ‘Each sequence of thecae forms a stipe, or branch, and colonies varied in the numbers of stipes that they possessed.’
      bag, pouch, bladder, blister
      View synonyms
    4. 1.4Anatomy The outer layer of cells of a Graafian follicle.
      • ‘The follicle is surrounded by a theca, derived from the stromal compartment of the ovary and is always separated from this compartment, throughout development and final oocyte maturation, by a basement membrane.’
      • ‘The term ‘follicle complex’ has been proposed to include the follicle, basement membrane, and the theca, including its blood vessels.’


Early 17th century: via Latin from Greek thēkē case.