Morphometric estimate of gas-exchange tissue in the new-born tammar wallaby, Macropus eugenii

Abstract

The lung of the new-born marsupial is at the terminal air sac stage of development. The maturational status of the lung of new-born tammar wallaby was assessed using established morphometric techniques and the results were compared with data from a morphometric study of the lung of the rat. Volume densities of the parenchyma and non-parenchyma, conducting airways and blood vessels, the relative volumes of airspace and tissue, the thickness and the composition of the septa differed between the two species. In addition the volume of capillaries and the surface area of the effective gas-exchange tissue was greater in the new-born rat than in the new-born tammar pouch young. The lung of the new-born tammar appears to be at an earlier phase of the terminal air sac stage than that of the new-born rat. Lung development up to birth appears to be commensurate to the metabolic needs of the organism at birth.