Experimental regeneration of the lungs

: In experiments on 150 guinea pigs, processes of lung wound healing were followed and the more active cellular sources of regeneration were identified. Measurements of cyclic adenosine monophosphate components in the course of lung healing indicated that histologic and electron-microscopic studies would be more informative if done at days 1, 3, 4, 7, and 14 after lung damage. Both cellular and intracellular mechanisms of regeneration were involved in the healing processes. The type II pneumonocyte be designated as a cambial cell of pulmonary parenchyma, for this cell displays the highest proliferative potency and is responsible for the epithelial lining of newly formed alveoli. The formation of these is shown to be assured through functional activity of all cellular alveolar elements (involving intracellular hyperplasia and hypertrophy of ultrastructures and especially dynamic morphological and functional alterations in osmiophilic bodies of type II pneumonocytes) and capillary neoformation.