STEREO-ELECTRON MICROSCOPY AND ENERGY-DISPERSIVE X-RAY-ANALYSIS OF AVIAN RETICULOCYTES

  • 1 January 1979
    • journal article
    • research article
    • Vol. 19  (3) , 239-249
Abstract
Utilizing the techniques of stereo-electron microscopy (stereo-EM) and energy-dispersive X-ray analysis (EDX), aspects of the ultrastructure of avian [chicken] reticulocytes were studied. Stereo-EM of thin sections (0.10-0.25 .mu.m thick) stained with uranyl and Pb revealed the 3-dimensional arrangement of 25 nm chromatin fibers on the tangential surfaces of nuclei. Use of the Bernhard staining procedure in combination with stereo-EM permitted a 3-dimensional view of the interchromatin spaces and channels leading to the nuclear pores, and of cytoplasmic polyribosomes. With either staining technique clusters and paracrystalline arrays of electron-dense granules with granule diameters approximately 1/2 that of monomer ribosomes were frequently encountered in the cytoplasm. These granules were highly electron-dense in unstained specimens and identified as intracellular ferritin on the basis of the similarity of their ultrastructural morphology to that of horse spleen ferritin and their high content of Fe as determined by EDX. It is unlikely that these granules represent toxic products of phenylhydrazine treatment (Heinz body). Heinz bodies cannot be visualized in unstained preparations, do not reveal the same granular structure, and do not contain significant amounts of Fe above background. The occurrence of intracellular ferritin was discussed in light of current concepts of Fe transport and storage during erythropoiesis.