The oesophageal pouches (also known as sugar glands) are a pair of pouches connected to the oesophagus of all molluscs, and represent a synapomorphy of the phylum.

Morphology

Usually forming a pair of lateral structures, oesophageal pouches take various forms, but usually account for a fair portion of the anterior volume of the creeping molluscs and scaphopods. There is a single pouch ventral to the rear of the

radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...

in some nudibranch sea slugs. The pouches are lined with ciliated

secretory cell 440px Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classica ...

Function

The pouches contain digestive enzymes that break down starch and other polysaccharides, and also extrude mucus.

Occurrence

The features are considered ancestral to molluscs and are present in

monoplacophora Monoplacophora , meaning "bearing one plate", is a polyphyletic superclass of molluscs with a cap-like shell inhabiting deep sea environments . Extant representatives were not recognized as such until 1952; previously they were known only from ...

ns, but have been secondarily lost in the Heterobranchia. However, it is not certain that all oesophageal diverticulae are homologous.

References

{{Gastropod anatomy Mollusc anatomy