Histology of lilium anther . Tapetum lining the pollen sacs .
百合花药结构,绒毡层衬在花粉囊内。
Males sit in groups with their throat sacs inflated , clattering their bills , waving their heads and quivering their wings .
男性坐在他们的喉咙群体囊膨胀,辚他们的帐单,挥舞著他们的头和颤抖的翅膀。
The air sacs are surrounded by a dense network of minute blood vessels , or capillaries , which connect to the heart .
这些气囊被连接着心脏的浓密的毛细血管网包围着。
Lungs are more complex than either of these organs , containing several different cell types that form delicate , hairlike capillaries and a maze of branching air sacs .
But could it function as that complex organ , whose thousands of branching airways contain millions of air sacs that exchange oxygen and carbon dioxide ?