Exocrine cells

The pancreas is a gland in the abdomen lying in the curvature of the stomach as it empties into the duodenum. The pancreas functions primarily as an exocrine gland, although it also has endocrine function. The exocrine cells of the pancreas are called acinar cells. They produce an alkaline fluid known as pancreatic... 

Noda T, Ogawa K. Golgi apparatus is one continuous organelle in pancreatic exocrine cell of mouse. Acta Histochem Cytochem 1984 17 435—451. 

Genetic mannosidosis has been described in man, Angus cattle and Murray Gray cattle, and is characterized by a deficiency of a-mannosidase leading to storage of excess mannose-rich oligosaccharides in lysosomes. Pathologically, there is vacuolation of reticuloendothelial cells in the liver and lymph nodes, pancreatic exocrine cells, and neurons. Affected cattle are ataxic, uncoordinated, fail to thrive, and die in the first year of life. 

Why this elaborate mechanism for getting active digestive enzymes into the gastrointestinal tract Synthesis of the enzymes as inactive precursors protects the exocrine cells from destructive proteolytic attack. The pancreas further protects itself against self-digestion by making a specific inhibitor, a protein called pancreatic trypsin inhibitor (p. 231), that effectively prevents... 

FIGURE 23-24 The endocrine system of the pancreas. In addition to the exocrine cells (see Fig. 18—3b), which secrete digestive enzymes in the form of zymogens, the pancreas contains endocrine tissue, the islets of Langerhans. The islets contain a, /3, and S cells (also known as A, B, and D cells, respectively), each cell type secreting a specific polypeptide hormone. 

There have been a couple of recent and excellent reviews of the ultrastructure of exocrine cells in general (Quennedey, 1998) and pheromone-secreting cells in social insects in particular (Billen and Morgan, 1998). This chapter attempts to survey the structural diversity of cells that produce sex pheromone in insects, particularly from a phylogenetic perspective, in part based on advances made... 

Figure 11. Schematic of the intracellular transport pathway of enzymes and precursors in the pancreatic exocrine cell (based on the data presented...

Q12 The pancreas has both endocrine and exocrine cells. What is the difference between endocrine and exocrine secretions ... 

Inflammation of the pancreas, pancreatitis, can be a consequence of excessive alcohol intake and causes severe pain. In chronic pancreatitis the exocrine cells which produce enzymes are damaged and smaller quantities of enzyme are released into the gut so that a major portion of the diet remains undigested and is not absorbed. Patients suffer malnutrition and weight loss. 

The peptide hormone somatostatin inhibits secretion from a wide variety of both endocrine and exocrine cells. It functions as a neurotransmitter and plays an important role in the regulation of cell proliferation and differentiation. Somatostatin exerts its effects through binding to specific surface membrane receptors. Somatostatin receptors are membrane glycoproteins with five different subtypes distributed in a variety of tissues throughout the body. 

Nishimura M, Kakizaki M, Ono Y, et al. JEAP, a novel component of tight junctions in exocrine cells. J Biol Chem 2002 277 5583-5587. 

The pancreas contains endocrine cells, which secrete hormones directly into the bloodstream, and exocrine cells, which secrete zymogen precursors of digestive enzymes into the upper small intestine. The endocrine tissue contains cell clusters known as islets of Langerhans, which contain at least four different cell types (A, D, P, and B), each specialized for synthesis of one hormone. The A cells produce glucagon the D cells, somatostatin and the P cells, a recently discovered pancreatic hormone. Insulin is synthesized in the B cells, which sense glucose levels and secrete insulin in response to increased levels of blood glucose. 

Al Martini s serum levels of pancreatic amylase (which digests dietary starch) and pancreatic lipase were elevated, a finding consistent with a diagnosis of acute and possibly chronic pancreatitis. The elevated levels of these enzymes in the blood are the result of their escape from the inflamed exocrine cells of the pancreas into the surrounding pancreatic veins. The cause of this inflammatory pancreatic process in this case was related to the toxic effect of acute and chronic excessive alcohol ingestion. 

Membrane type Hepatocyte volume 5,000 /tm Pancreatic exocrine cell volume 100p.m ... 

The relative amount of membrane (%) is presented for a hepatocyte and a pancreatic exocrine cell. ER = endoplasmic reticulum. Adapted from [122], p. 553. 

The scelionid egg parasitoid Telenomus heliothidis interrupts egg development in its host R. virescens. A regulatory substance, apparently produced and secreted by the exocrine cells of the common oviducts of the parasitoid, was responsible for the rapid arrestment of host embryogensis (77), Necrosis of host tissue is also associated with parasitism. However, if oviposition was interrupted prior to egg deposition, the resulting pseudoparasitized host exhibited arrestment of embryogenesis but no tissue necrosis. Apparently in this case the secreted substance was not associated with restructuring of host tissue for the nutrition of the parasitoid. Also, the mode-of-action and the nature of this regulatory substance is unknown. 

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