The function of the pylorus caeca of fish has been unknown since its detailed description in 345 BC. by Aristotle. He proposed three hypotheses about their function: “to store the food,” “to putrefy it,” and “to prepare it” (i.e., storage, fermentation, and digestion)..
Along the proximal gut of many fish species are blind diverticula called the pylorus caeca.
The pylorus caeca secretes a potent protease (trypsin), a potent amylase and a bile-activated lipase. The intestinal mucosa has lipolytic and amylolytic ferments, while bile has some amylolytic properties.
Definition of pyloric caecum
1 : one of the tubular sacs that open into the alimentary canal in the pyloric region of most fish. 2 : one of the tubular sacs that open into the heart chamber of an insect.
At the back end of the stomach — in front of or just at the beginning of the intestine — many fish have a few thin, blind tubes called the pyloric caeca. Not all fish have them, wrasse, pipefish and many catfish don’t have them.
Fish take food through the mouth and break it down in the esophagus. In the stomach, food is further digested and, in many fish, processed in finger-shaped sacs called pylorus caeca, which secrete digestive enzymes and absorb nutrients.
As in all vertebrates, the pancreas has two digestive functions. It is the source of: 1) exocrine secretion of digestive enzymes (proteases, lipases and carbohydrases) into the gut and 2) endocrine secretion of the hormones insulin and glucagon, which lower and raise blood sugar.
Fish without a stomach do not have an acidic phase during digestion. The site of secretion in teleost stomachs appears to be a single cell type that produces both HCl and enzyme(s). This is in contrast to mammals, where there are two types of cells, one for acid and one for enzymes.
In addition to digesting and absorbing feed, the gut is crucial for water and electrolyte balance, endocrine regulation of digestion and metabolism, and immunity.
The pyloric cavity is the lower or distal portion above the duodenum. The opening between the stomach and small intestine is the pylorus, and the very strong sphincter muscle that regulates the passage of chyme into the duodenum is called the pyloric sphincter.