Ingluvies

Ingluvies 

the crop, or widened portion of the esophagus, in many mollusks, insects, and birds, which serves to accumulate, store, and sometimes also begin the chemical processing of food. In flies, butterflies, and other insects that use liquid food the ingluvies is represented by an unpaired sac mounted on a stalk; in the malarial mosquito it is paired; and in aphids, in addition to the unpaired ventral ingluvies, there are two dorsal ones. In bees the fermentative processing of flower nectar into honey takes place in the ingluvies. The expanded portions of the esophagus in annelid worms, nematodes, and nemerteans are also called ingluvies.

In predatory birds and a number of passerines the ingluvies is spindle-shaped, in birds of the Galliformes order it is a two-lobed pouchlike enlargement, and in the hummingbird it is a lateral process of the esophagus. The walls of the ingluvies, as well as of the esophagus in birds, usually secrete a fluid mucus that serves to moisten the food; in seed-eaters it serves to soften the food, and in some (for example, pigeons) it is used for fermentative processing. The bird ingluvies is capable of peristaltic movements, of ensuring the entry of food from the ingluvies into the stomach, and of regurgitating food or removing undigested remnants (bones, fur, or feathers) while the bird is feeding nestlings. Sand grouses that inhabit the desert zone transport water for their nestlings in the ingluvies. In pigeons, beginning with the eighth day of incubation, the epithelial cells that line the ingluvies undergo fatty degeneration, are torn away, and together with the secretion of the ingluvial glands form a whitish fluid (“ingluvial milk”) that contains up to 30 percent fat and 15 percent protein and serves as food for the nestlings. In the flamingo the secretions of the esophagus walls, which contain, besides nutritive matter, blood, are used as food for the baby birds. When the males of bustards, some Tetraonidae, and pigeons utter their mating calls, processes of the esophagus fill with air and serve as resonators.

N. V. KOKSHAISKII