D. Alveoli E. Associated blood vessels, lymphatics, nerves, C.T. Figure 7. Illustrates the microanatomy of bronchioles and alveolar sacs. A few alveoli bud from their walls. These are thin walled tubules. Their wall is interrupted by the opening of many thin walled outpouchings, the alveoli .
Alveolar sacks open only into the alveolar ducts.
The space into which alveolar sacks open in the alveolar duct is called the atrium . Sows the microanatomy of the alveolus. I pneumocytes function as lining cells of alveoli and thought to have the potential of differentiating into Type II pneumocytes . Alveoli are supplied by capillaries from branches at the level of the alveolar duct. Venules arise from the alveolar septa and from the pleura , run independently of arterioles and form the pulmonary veins which return the blood to the heart.