https://upload.wikimedia.org/wikipedia/commons/7/7e/Blausen_0699_PancreasAnatomy2.png

Organ which secretes a fluid containing enzymes that aid in the digestion of food.[AAO]

The mature pancreas of higher vertebrates and mammals comprises two major functional units: the exocrine pancreas, which is responsible for the production of digestive enzymes to be secreted into the gut lumen, and the endocrine pancreas, which has its role in the synthesis of several hormones with key regulatory functions in food uptake and metabolism. The exocrine portion constitutes the majority of the mass of the pancreas, and contains only two different cell types, the secretory acinar cells and the ductular cells. The endocrine portion, which comprises only 1-2% of the total mass, contains five different cell types, which are organized into mixed functional assemblies referred to as the islets of Langerhans

uberon

pancreatic

In the hagfish and lampreys (our most primitive vertebrate species of today), the first sign of 'a new organ' is found as collections of endocrine cells around the area of the bile duct connection with the duodenum. These endocrine organs are composed of 99% beta cells and 1% somatostatin-producing delta cells. Compared to the more primitive protochordates (e.g. amphioxus), this represents a stage where all previously scattered insulin-producing cells of the intestinal tissue have now quantitatively migrated to found a new organ involved in sensing blood glucose rather than gut glucose. Only later in evolution, the beta cells are joined by exocrine tissue and alpha cells (exemplified by the rat-, rabbit- and elephant-fishes). Finally, from sharks and onwards in evolution, we have the islet PP-cell entering to complete the pancreas.[well established][VHOG]

UBERON:0001264

As a secretory organ serving exocrine and endocrine functions, the pancreas is specific to the vertebrates[PMID:16417468] Hagfishes and lampreys are unique in the complete separation of their endocrine pancreas (islet or- gan) and their exocrine pancreas (50). The endocrine and exocrine pancreas are coassociated in crown gnathostomes (50). In Branchiostoma and Ciona, there is no diverticulum as there is in hagfishes, lampreys, and gnathostomes, only dispersed insulin-secreting cells in the walls of the gastrointestinal tract (51, 52), The zebrafish does not have a discrete pancreas. Exocrine pancreatic tissue can be found scattered along the intestinal tract. The acinar structure of the exocrine pancreas is very similar to that of mammals and comprises cells with a very dark, basophilic cytoplasm

• exocrine pancreas
• endocrine pancreas

• pancreatic juice

• pancreas primordium

• pancreatic fat pad
• parenchyma of pancreas
• pancreatic lymph node
• exocrine pancreas
• endocrine pancreas
• pancreas secretion
• stroma of pancreas
• capsule of pancreas
• dorsal pancreas
• ventral pancreas
• pancreas mesenchyme