Meeting Abstract
The lungs of Xenopus laevis start forming at an early premetamorphic stage and continue developing into the adult form well after metamorphosis has occurred. Similar to other animals, lung development in X. laevis involves both endodermal and mesodermal derivatives to establish efficient respiratory structures. Here, we examine the growth of both the endodermal and mesodermal components of X. laevis lungs from premetamorphic to postmetamorphic stages (NF47 to NF 66). Tadpoles at NF stages 47, 49, 54, 60, 64, and 66 were anesthetized in 0.1% MS-222 and rinsed in 1X PBS. Before the lungs were removed by dissection, an area of the ventral surface, that included the region of the abdomen and heart, was measured in order to standardize values among individuals of different body size. Lungs, in 1X PBS, were maximally inflated with air using a syringe needle inserted into the laryngotracheal groove. Lung inflation was viewed from the dorsal side and digitally recorded. Measurements of lengths and widths were made using ImageJ and individual video frames of maximally inflated lungs. Measurements of right and left lungs were averaged for each individual. These measurements were used to calculate parameters such as surface area, cross-sectional area, and volume. Our results indicate strong correlations between the measured ventral surface area and the growth of both the endodermal and mesodermal derivatives of the lung. Stage specific comparisons standardized for body size suggest that lung volumes increase over the entire range of the developmental stages included in our study. The vascularized mesodermal component of the lung increased significantly as the tadpoles approached metamorphosis.
