Lung cells must have 2 important features to improve their performance as part of the lung. Lung cells must be flexible to allow them to be stretched as a part of breathing. They must also have thin walls to allow gasses to pass through them during gas transfer.
Lung tissue has a lace-like appearance under the microscope due to the proliferation of alveoli with single cell thick walls. The alveoli have a good blood supply, with numerous capillaries delivering red blood cells (white) to the tissues to pick up oxygen and release carbon dioxide. Bronchioles deliver air to the alveoli and are lined with cilia (black) that remove particles and other debris from the lungs.