DOI: 10.5176/2382-5685_VETSCI15.05
Authors: J.N. Maina
Abstract:
Morphometric studies of the developing avian lung are few and partial. Here, the changes in the volume densities of the main structural components of the lung of the domestic fowl, Gallus gallus variant domesticus, namely the parenchyma (exchange tissue), the air spaces (lumina of secondary bronchi and the parabronchi) and the blood vessels (branches of the pulmonary artery and interparabronchial veins and arteries) were quantified. Three corresponding embryonic- and pulmonary growth phases were observed. For the lung, a proliferation phase occurred from day 6 to 9 of incubation, an equilibration one from day 10 to 14 and a consolidation stage happened between days 15 and 20. It was observed that the lung developed through intricate changes in the structural components. Between days 15 and 17, the volume density of the exchange tissue decreased from 67{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} to 18{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} while that of the blood vessels increased by the same margin, i.e., from 4{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} to 53{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465}: the volume density of the air-spaces remained fairly constant during the development of the lung. The changes in the volume densities of the structural components may be significantly determined by the firmness and the rigidity of the developing lung. Very early, i.e., from about day 6 of incubation, dorsolaterally, the lung is deeply attached to the vertebrae and the ribs and is attached to the horizontal septum on the ventral aspect. The processes of substitution and transformation of the structural components of the developing chicken lung indicate that space is limiting in the lung and may significantly determine the developmental dynamics of the lung.
Keywords: birds; domestic fowl; respiratory system; embryo; lung; development; morphometry
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