sac

• 指动物体内的囊状结构或封闭空腔，也指植物中的囊状器官，如花粉囊或苔藓的孢蒴。

A noun referring to an enclosed space, a bag-like structure in an animal, or a case or sheath such as a pollen sac or moss capsule.

1. B2formalscientific

   A cavity or enclosed space within an organism, often containing fluid.

   囊

   • The air sac in the bird's lungs helps with respiration.
   • The plant's pollen sac releases grains during pollination.
   • The insect's egg sac protects the developing larvae.

   同义词bladderbursacavitycystpouchvesicle

2. Pollen sac or moss capsuleC1formalscientific

   A case or sheath that contains pollen in plants or spores in mosses.

   花粉囊或藓类孢蒴

   • The pollen sac of the flower burst open to release its contents.
   • Moss capsules are specialized sacs that hold spores.
   • The anther contains four pollen sacs in most flowering plants.

   同义词capsulesporangiumtheca

3. Bag-like structure in animalsB2formalmedical

   A structure resembling a bag or pouch in an animal's body, often for storage or secretion.

   囊

   • The yolk sac provides nutrients to the developing embryo.
   • The venom sac of a snake stores toxic fluid.
   • The swim bladder is a gas-filled sac that helps fish control buoyancy.

   同义词bagbladderbursapouchvesicle