Stomach Structure and Function in Three Species of Macropodine Marsupials.

Abstract

The topographic anatomy and the histology of the stomach are described for three species of macropodines, Macropus eugenii, M. giganteus and Thylogale thetis. together with information on the movement of digesta through the stomach. The three regions of the macropodine stomach were defined as sacciform fore stomach, tubiform fore stomach, and hind stomach. In both species of Macropus the largest region was the tubiform fore stomach, but in T. thetis it was the sacciform fore stomach. The opening between sacciform and tubiform fore stomachs in all three species is wide, but the two gastric regions are delimited by a permanent ventral fold. The position of the cardia in relation to this fold differed among species, and together with the presence (M. eugenii). reduction (M. giganteus) or absence (T. thetis) of a gastric sulcus, could be correlated with the initial distribution and subsequent dispersion of barium sulphate in radiographic studies. The wall of the sacciform and tubiform fore stomachs is differentiated into taeniae and nonpermanent haustra and semilunar folds. From this and earlier studies it appears that these structures are mainly responsible for the separation within the macropodine stomach of particulate from liquid digesta.