The Tubular Early Endosome
Endosomes are pleiomorphic organelles that are often difficult if not impossible to identify in thin sections under the electron microscope in the absence of either an electron dense endocytic tracer in their lumen or an immunocytochemical marker. As a consequence, horseradish peroxidase has been widely used as a nonspecific fluid phase endocytic tracer in electron microscopic studies of endosomes and endocytosis. The horseradish peroxidase (HRP) method involves incubating cells in medium containing HRP for times ranging from a few minutes to several hours. The cells are then fixed and incubated with hydrogen peroxide and DAB. As a result of the peroxidase reaction the DAB is polymerised and rendered insoluble in situ. Finally, the cells are treated with osmium tetroxide to osmicate them, and render electron dense the poly DAB, before being embedded.
KeywordsPC12 Cell Mitotic Cell Early Endosome Late Endosome Peroxidase Reaction
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