COMPARISON OF THE ULTRASTRUCTURE OF ADRENALINE AND NORADRENALINE STORAGE GRANULES OF BOVINE ADRENAL-MEDULLA

  • 1 January 1979
    • journal article
    • research article
    • Vol. 20  (1) , 76-82
Abstract
The ultrastructure of the membranes of noradrenaline (NA, norepinephrine) and adrenaline (A, epinephrine) granules of the bovine adrenal medulla was analyzed by transmission, negative staining and freeze-etch EM. The 2 types of storage granules can be distinguished mainly by 2 morphological criteria: The NA-granules have a more electron dense matrix core than the A-granules; the NA-granules revealed less asymmetry in the distribution of intramembrane particles (nPF:nEF [mean number of protoplasmic face particles: mean number of endoplasmic face particles] = 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 2 fracture faces on freeze-etch EM were very similar for the 2 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[endoplasmic]-fracture faces and 11.4 .+-. 2.7 nm (A-granules) and 9.8 .+-. 2.4 nm (NA-granules) for the P[protoplasmic]-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. Morphometric analyses of sectioned bovine adrenal medulla revealed that the chromaffin granules on an average account for .apprx. 13.5% of the cytoplasmic volume in the total population of chromaffin cells.