MORPHOMETRIC ESTIMATE OF GAS-EXCHANGE TISSUE IN THE NEWBORN TAMMAR WALLABY, MACROPUS-EUGENII

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 w allaby 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, con ducting airways and blood vessels, the relative volumes of airspace an d tissue, the thickness and the composition of the septa differed betw een the two species. In addition the volume of capillaries and the sur face 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 appe ars to be commensurate to the metabolic needs of the organism at birth . (C) 1998 Elsevier Science B.V. All rights reserved.