ISSN:
1432-0878
Keywords:
Exocrine pancreas
;
Frog
;
Ultrastructure
;
Intracellular transport
;
Autoradiography
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The route by which secretory proteins are transported in the frog exocrine pancreas cell was investigated by an ultrastructural and electron microscope autoradiographic analysis of in vivo 3H-leucine labelled tissue. The ultrastructure of the cell is characteristic of serous epithelial cells and resembles that of mammalian exocrine pancreas cells very closely. Autoradiographic results revealed that the proteins, after being synthesized in the rough endoplasmic reticulum (RER), are transported through the Golgi cisternae to condensing vacuoles which subsequently change into secretory granules. The determination of the timing of this transport was complicated by a very slow turnover of leucine in the frog. Nevertheless, by a semi-quantitative approach, some time characteristics could be estimated: about 11 min after the onset of their synthesis the proteins enter the Golgi system, and about 25 min later the condensing vacuoles. Secretory granules become labelled between 60 and 120 min. These results are discussed, also in relation to the transport route and kinetics in mammalian tissue.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00221350
