Bird, proventriculus (Gross, Medium)

Structure List Esophagus Proventriculus Ventriculus Duodenum

In all birds, a PROVENTRICULUS and GIZZARD have evolved from the cranial and caudal parts of the stomach, respectively. The proventriculus produces gastric secretions that mix with the food as it is ground up by the gizzard. The gizzard has a thick, muscular wall with a tough lining and usually contains small stones that have been swallowed. Its incredible capability has led to a mandatory restriction on the use of lead shot for hunting purposes. After being accidentally ingested, the shot is actually broken down in the gizzards of geese and ducks, leading to lead toxicity. Recall that birds have lost their teeth, so the gizzard plays an important role in the mechanical breakdown of their food.