Biomaterial Database

Ultrastructure of intercellular junctions in the rat exocrine pancreas stimulated by pancreozymin. 1979

K Tsukiyama

Intercellular junctions in the exocrine pancreas, through which pancreatic enzymes may leak out from the lumen into the intercellular spaces, were studied in the rat by means of electron microscopy using tannic acid as a tracer and freeze-fracture methods as well as conventional thin sections. In thin sections and freeze-fracture replicas from the pancreas stimulated or not stimulated by exogenous pancreozymin, tight junctions were located between adjacent cells of the acinus or duct at the level just below the lumen. Observation of freeze-fracture replicas revealed that the number of strands or furrows in the tight junction did not differ significantly between the two groups but the width of the tight junction area was narrower and the distance between neighboring strands or furrows in the junction was smaller in the stimulated pancreas than in the control pancreas. Tannic acid, the molecular weight of which is smaller than that of pancreatic enzymes, could not pass beyond the tight junction area into the lumen. This study suggests that the pancreatic enzymes can not leak out from the glandular lumen into the intercellular spaces by dissociation of intercellular junctions even if the pancreas is stimulated by a high concentration of pancreozymin.

UI	MeSH Term	Description	Entries
D007365	Intercellular Junctions	Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)	Cell Junctions,Cell Junction,Intercellular Junction,Junction, Cell,Junction, Intercellular,Junctions, Cell,Junctions, Intercellular
D008297	Male		Males
D010179	Pancreas	A nodular organ in the ABDOMEN that contains a mixture of ENDOCRINE GLANDS and EXOCRINE GLANDS. The small endocrine portion consists of the ISLETS OF LANGERHANS secreting a number of hormones into the blood stream. The large exocrine portion (EXOCRINE PANCREAS) is a compound acinar gland that secretes several digestive enzymes into the pancreatic ductal system that empties into the DUODENUM.
D002766	Cholecystokinin	A peptide, of about 33 amino acids, secreted by the upper INTESTINAL MUCOSA and also found in the central nervous system. It causes gallbladder contraction, release of pancreatic exocrine (or digestive) enzymes, and affects other gastrointestinal functions. Cholecystokinin may be the mediator of satiety.	Pancreozymin,CCK-33,Cholecystokinin 33,Uropancreozymin
D005614	Freeze Fracturing	Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.	Fracturing, Freeze,Fracturings, Freeze,Freeze Fracturings
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D051381	Rats	The common name for the genus Rattus.	Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus