種々の免疫電子顕微鏡法を用いたウシ副腎皮質アドレノドキシンの局在

Abstract

Adrenodoxin has been reported to be heterogenously distributed among the mitochondria within a single parenchymal cell of the adrenal cortex by a pre-embedding immunocytochemical method with horseradish peroxidase-labeled Fab' antibodies. Using various immunoelectron microscopic techniques, I re-examined the distribution of adrenodoxin among the mitochondria in the parenchymal cells of bovine adrenal cortex. By post-embedding immunocytochemistry in combination with the protein A-gold technique, gold particles were seen on all the mitochondria examined in the parenchymal cells. By non-embedding immunocytochemistry (immuno-cryoultramicrotomy) in combination with the protein A-gold technique or a peroxidase-labeled streptavidin-biotin method, all of the mitochondria examined in the parenchymal cells were labeled with gold particles or 3, 3'-diaminobenzidine reaction products. By pre-embedding immunocytochemistry examining transverse ultrathin sections prepared from cryostat sections, the mitochondria in contact with the surface of the cryostat sections were stained at a higher percentage than the mitochondria within the cryostat sections. These results suggest that adrenodoxin is distributed homogeneously among the mitochondria within a parenchymal cell and that mitochondrial heterogeneity is caused by uneven antibody penetration into mitochondria in the pre-embedding method. Within the mitochondria in the parenchymal cells, adrenodoxin was stained on the matrix and inner mitochondrial membrane. Adrenodoxin was also stained on the round and electron-dense intramitochondrial bodies, which were often observed in the mitochondria of parenchymal cells in the zona glomerulosa and in the outer layer of the zona fasciculata. By quantitative immunoelectron microscopy, the density of gold particles on mitochondria in the parenchymal cells of the zona glomerulosa was two to three fold lower than that of the zona fasciculata, while that of the zona reticularis was similar to that of the zona fasciculata. The merits and demerits of pre-, post-, and non-embedding immunocytochemistry are discussed.