Ventrolateral view, right side

Ventrolateral view, left side

Ventrolateral view, right side

The pleura is an organ that is primarily epithelial tissue.  It covers the thoracic organs and lines the thoracic cavity.  Functionally it is important because it secretes fluid that lubricates the surfaces it is associated with, helps reduce heat buildup, and is responsible for surface tension that holds the lungs against the thoracic wall.