cell

The central area surrounded by veins. It can be closed by veins or open.

• The vein forming the boundary of the cell along the costal margin is known as the subcostal vein q.v.
• The vein forming the lower boundary towards the dorsum is called the median vein.
• In the case of butterflies, the cell is closed by a vein connecting the origins of veins 6 to 4 along the top of the cell which is known as discocellular vein.