MORPHOMETRIC ANALYSIS OF POSTNATAL LUNG DEVELOPMENT IN THE TAMMAR WALLABY - LIGHT-MICROSCOPY

Postnatal growth of the lung in the tammar wallaby, Macropus eugenii, was investigated using morphometric techniques with light microscopy. Lung volume, parenchymal and non-parenchymal volume densities were mea sured. Volume densities of parenchymal airspace and tissue and non-par enchymal conducting airways and large blood vessels were determined. L ung volume and all the other parameters that were measured showed a bi phasic increase in relation to increase in body mass. All parameters, with the exception of airway volume, increased relatively slowly in re lation to increase in mass in the first 70 days after birth, when the pouch young are ectothermic. Between 70 and 180 days, during the perio d of transition from ectothermy to endothermy, the parameters increase d more rapidly, suggesting accelerated lung growth in preparation for the extra metabolic demands associated with the establishment of therm oregulatory control in the pouch young. Specific lung volume in the ad ult tammar is lower than that of eutherians of equivalent mass, howeve r, the parenchymal volume is relatively high. (C) 1998 Elsevier Scienc e B.V. All rights reserved.