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

Abstract Examination of the topographical anatomy of the stomach complex and intestinal tract of an adult male and a newborn female pigmy hippopotamus ( Choeropsis liberiensis ) shows that the stomach consists of four chambers, the first three constituting the proventriculus and the fourth the glandular stomach. The proventriculus is made up of a visceral and parietal blind sac opening into a connecting chamber, which in turn opens into the glandular compartment. The walls of the proventricular chambers are covered with villi and non‐glandular mucous membrane. The significant difference between the animals is that whereas the connecting chamber of the adult stomach lies transversely deep in the cranial part of the abdomen and connects with the glandular chamber on the right side, that of the newborn lies almost vertically and connects ventrally with the glandular compartment situated on the floor of the abdomen. A groove which in the adult runs more or less horizontally from the cardia through the visceral sac and connecting chambers is aligned almost vertically in the newborn. In the adult the connecting chamber is the largest compartment, but in the neonate the visceral blind sac and the glandular compartment are proportionally larger. Functional aspects of these anatomical differences are discussed in relation to suckling behavior. The intestine consists of a continous tube. There is no caecum; instead the junction between small and large intestine is distinguished by an increase in diameter, a change in epithelial lining, and anastomoses of the jejunal and colic arteries. Large amounts of fat are present in the omentum and mesentery of the neonate.