• Operculum (animal)
  Operculum (animal)
  An operculum is an anatomical feature, a stiff structure resembling a lid or a small door that opens and closes, and thus controls contact between the outside world and an internal part of an animal...
  
  , a stiff structure resembling a lid or a small door that opens and closes
  • Operculum (gastropod)
    Operculum (gastropod)
    The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
    
    , a lid on the shell of some gastropods
  • Operculum (bryozoa)
    Operculum (bryozoa)
    In the bryozoan order Cheilostomata, the operculum is a calcareous or chitinous lid-like structure that protects the opening through which the polypide protrudes....
    
    , a lid on the orifice of some bryozoans
  • Operculum (fish)
    Operculum (fish)
    The operculum of a bony fish is the hard bony flap covering and protecting the gills. In most fish, the rear edge of the operculum roughly marks the division between the head and the body....
    
    , a flap of the bony fish covering the gills
  • Operculum (bird), a structure which covers the nares of some birds
• Operculum (botany)
  Operculum (botany)
  An operculum, in botany, is a term generally used to describe a structure within a plant, moss, or fungus acting as a cap, flap, or lid. In plants, it may also be called a bud cap.Examples of structures identified as opercula include:...
  
  , various lids and flaps pertaining to plants, algae and fungi
• Operculum (brain)
  Operculum (brain)
  Operculum, derived from Latin, meaning "little lid", refers to the cerebral cortex on the outside surface of the brain bordering the lateral sulcus, and the roof and floor of the lateral sulcus. Neuroscience divides the operculum into orbital, frontal, parietal and temporal regions, after the...
  
  , a part of the human brain
• Operculum (dentistry), a small flap of tissue which may cover an erupting or partially erupted molar
• Operculum (pregnancy), the cervical mucus plug
  Cervical mucus plug
  A cervical mucus plug ' is a plug that fills and seals the cervical canal during pregnancy. It is formed by a small amount of cervical mucus.The mucus plug acts as a protective barrier by deterring the passage of bacteria into the uterus....
  
   that blocks the cervix of the uterus after conception

See also

• Dehiscence (botany)
  Dehiscence (botany)
  Dehiscence is the opening, at maturity, in a pre-defined way, of a plant structure, such as a fruit, anther, or sporangium, to release its contents. Sometimes this involves the complete detachment of a part. Structures that open in this way are said to be dehiscent...
  
  , the opening of a plant structure, such as a fruit, anther, or sporangium, to release its contents. This sometimes involves an operculum.