Bronchial tree Architecture in Mammals of Diverse Body Mass

Abstract

SUMMARY:The anatomy of mammal's lung air space constitutes the bronchial tree which disposition is associated to air flux dynamics. Casts obtained from human, pig and rat lungs were studied to analyze possible differences of the bronchial tree architecture in mammals with diverse dimensions and posture. Air spaces were filled with polymers through trachea followed by acid corrosion. Tracheal and main bronchial division's diameters were measured to relate with body mass using allometry. The results revealed a dichotomic bronchial branching pattern in the human casts and a monopodial pattern in animals. In allometric relationship trachea was larger in rats, then pigs and lastly in humans, differences were statistically significant, the same occurs in right bronchus, as in the left bronchus there was no difference between rat and pig. The linear relationship between the human tracheal diameters was 1.2 times larger than the pig and 6.7 times larger than the rat; the pig tracheal diameter was 5.6 times larger than the rat. Quadruped position of the pig and rat is linked to a horizontal air way while the erect position, biped in human, correspond to a vertical air way. A big mammal shows less respiratory frequency than small mammals. Mammals with small, medium and high body mass allied to diverse posture and habits was compared revealing morphological differences in the bronchial trees as different allometric correlations between quadruped animals and human biped.

Generation of Pig Airways using Rules Developed from the Measurements of Physical Airways

“…The tree generated from the algorithm was comparable to the geometry extracted from CT [29-31], which showed monopodiality, and is comparable to the dog lung airways [22]. The generated tree morphology also showed similarity with that reported in previous studies [17,26,33]. …”

“…Details of pig airway geometry are scarce or incomplete [25,26]. Since the morphology of animal airways can be significantly different from humans, approximating pig airway geometry by its human counterpart can lead to errors in both computational and numerical studies.…”

The Creation and Statistical Evaluation of a Deterministic Model of the Human Bronchial Tree from HRCT Images

“…The iterative redistribution of the sub-volume seeds in the case where the tree expansion stops under the condition of TB length; this should eradicate the very few, but still important unrealistically large acini predicted by the model (Fig 9). Furthermore, the parameters affecting branching and geometric symmetry could be examined and configured for the adaptation of the model with respect to species (increased symmetry vs monopody) [71]. Additionally, the incorporation of features of disease, such as the bronchial cross-section shape and perimeter or radius of curvature, as well as variations referring to respiratory motion would be necessary for the model to provide more precise calculations for diagnosis and therapy.…”

Dry Lung as a Physical Model in Studies of Aerosol Deposition

“…Unfortunately, the MMPD software has not been adapted to calculate deposition in pig's lung. Considering that human and porcine lungs have similar overall volume and the alveolar size as well as similar number of bronchial generations [17,18], we expect that the software developed for the human lungs will adequately describe deposition in the porcine lungs provided that the model parameters are chosen correctly.…”

“…First, as applied to modeling deposition in human lungs, a certain difference in the anatomy of swine and human lungs should be taken into account. While the human airway tree has a bipodial branching pattern, branching pattern of the swine Deadlocks in the lung areas slowly exchanging air for carbon dioxide are colored in orange tree is monopodial with larger ''parent'' bronchus giving rise to smaller side-branches [17]. Second, preparation procedure might result in some changes in the lung structure due to shrinkage of collagen.…”