Comparative and functional morphology of the stomach in the adult and newborn pigmy hippopotamus(Choeropsis liberiensis)

The connecting chamber is oriented in a dorsal-to-ventral direction in the newborn to assist with passage of milk into the glandular stomach; the orientation changes in the adult to promote retention of ingesta and its movement between compartments of the fore stomach.

“The connecting chamber is oriented in a dorsal-toventral direction in the newborn to assist with passage of milk into the glandular stomach; the orientation changes in the adult to promote retention of ingesta and its movement between compartments of the fore stomach (Macdonald and Hartman 1983).”

The mucosal epithelium of the fore stomachs is lined with finger-like papillae, each varying in length, thickness, and shape; these papillae are less prominent in the newborn.

“The mucosal epithelium of the fore stomachs is lined with finger-like papillae, each varying in length, thickness, and shape; these papillae are less prominent in the newborn (Macdonald and Hartman 1983;Endo et al. 2001).”

The four stomach compartments of C. liberiensis are similar to those of a ruminant and include the nonglandular visceral and parietal blind sacs (also termed left and right diverticula), the vestibulum, the connecting chamber, and the customary glandular stomach.

“The four stomach compartments are similar to those of a ruminant and include the nonglandular visceral and parietal blind sacs (also termed left and right diverticula), the vestibulum, the connecting chamber, and the customary glandular stomach (Langer 1975;Macdonald and Hartman 1983).”

There is no cecum in C. liberiensis, but the junction between the large and small intestine is characterized by an increase in diameter and a change in the lining of the mucosal epithelium.

“There is no cecum (Macalister 1873), but the junction between the large and small intestine is characterized by an increase in diameter and a change in the lining of the mucosal epithelium (Macdonald and Hartman 1983).”

The blind sacs, ventriculus, and connecting chamber of C. liberiensis are further subdivided by a series of semilunar folds, 1-3 cm in height, derived from the tunica muscularis.

“The blind sacs, ventriculus, and connecting chamber are further subdivided by a series of semilunar folds, 1-3 cm in height, derived from the tunica muscularis (Langer 1975;Macdonald and Hartman 1983).”

The entire small intestine (duodenum, jejunum, ileum) of an adult female C. liberiensis is about 16 m long with an average diameter of 2.5 cm; the colon is about 2.5 m long.

“The entire small intestine (duodenum, jejunum, ileum) of an adult female is about 16 m long with an average diameter of 2.5 cm; the colon is about 2.5 m long (Macdonald and Hartman 1983).”

Hippos are called pseudo-ruminants or ruminant-like, with microbial fermentation in the fore stomachs supporting digestion through the production of volatile fatty acids and essential vitamins.

“Hippos are called “pseudo-ruminants” or ruminant-like, with microbial fermentation in the fore stomachs supporting digestion through the production of volatile fatty acids and essential vitamins (Langer 1975;Macdonald and Hartman 1983).”