D) Pleura

Macroscopic Appearance

The pleura is a thin layer of tissue which coats the surface of the lungs (the visceral pleura) and the internal surface of the thoracic cage (the parietal pleura), forming the pleural cavity. The surface is slippery, allowing sliding of the lung over the thoracic wall. The pleura is named for the region of the body which it faces; for instance, the pleura lining the mediastinum is the mediastinal pleura. The visceral and parietal pleura are only continuous at the hilum, where the layer reflects between the lung and the mediastinum.

Microscopic Appearance

The visceral pleura is closely adherent to the lung, through a thin layer of connective tissue. The epithelial layer is of the simple squamous variety.
The parietal pleura also consists of simple squamous epithelium with underlying loose connective tissue, allowing it to be separated from the underlying thoracic cage.


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