title: Comparison of the ultrastructure of adrenaline and noradrenaline storage granules of bovine adrenal medulla.
abstract: The ultrastructure of the membranes of noradrenaline (NA) and adrenaline (A) granules of the bovine adrenal medulla (Terland, O., T. Flatmark, and H. Kryvi, Biochim, Biophys. Acta 553, 460--468 (1979)) was analyzed by transmission, negative staining and freeze-etch electron microscopy. The two types of storage granules can be distinguished mainly by two morphological criteria: (a) The NA-granules have a more electron dense matrix core than the A-granules, (b) the NA-granules revealed less asymmetry in the distribution of intramembrane particles (nPF:nEF = 4,5:1) than the A-granules (nPF:nEF = 9:1). Thus, the trilaminar structure, negative staining pattern and size distribution of the intramembrane particles of the two fracture faces on freeze-etch electron microscopy were very similar for the two types of granules. Freeze-etching revealed a wide range of the particle size distribution for both fracture faces in both types of granules, with an average diameter of 12.6 +/- 2.7 nm (A-granules) and 10.2 +/- 2.8 nm (NA-granules) for the E-fracture faces and 11.4 +/- 2.7 nm (A-granules) and 9.8 +/- 2.4 nm (NA-granules) for the P-fracture faces. Some of the particles on the P-fracture face (outer surface of the membrane) revealed a subunit structure, most clearly seen in the specimens of NA-granules. Morhpometric analyses of sectioned bovine adrenal medulla revealed that the chromaffin granules on an average account for approx. 13.5% of the cytoplasmic volume in the total population of chromaffin cells.
mesh_terms: D000313:Adrenal Medulla / Q000648:ultrastructure*; D000818:Animals; D002417:Cattle; D002837:Chromaffin Granules / Q000378:metabolism / Q000648:ultrastructure*; D002838:Chromaffin System / Q000648:ultrastructure*; D004837:Epinephrine / Q000378:metabolism; D005613:Freeze Etching; D008854:Microscopy, Electron; D009638:Norepinephrine / Q000378:metabolism
chemical_list: D009638:Norepinephrine; D004837:Epinephrine