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Methylamine tungstate and tannic acid in fixation for high contrast and preservation of fine structure: application to myxomycete plasmodia
Author(s) -
Chestnut Matthew H.,
Cohen Arthur L.
Publication year - 1984
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1984.tb00497.x
Subject(s) - tannic acid , glutaraldehyde , organelle , fixation (population genetics) , fixative , staining , methylamine , biophysics , osmium tetroxide , chemistry , electron microscope , biology , cytoplasm , biochemistry , botany , chromatography , genetics , physics , gene , optics
SUMMARY The effects of several fixation methods for electron microscopy were compared, using macro‐plasmodia of Badhamia utricularis (myxomycete) as test objects. A brief osmium tetroxide (Os) exposure followed by a mixture of glutaraldehyde (GA) and tannic acid (TA) with subsequent treatment with methylamine tungstate (MAT) overcame most commonly encountered difficulties in fixing these structures. Lead staining of the sections was necessary to bring out the range of densities inherent in the delicate detail of ground cytoplasm, membranes, and organelle structure retained by Os/GA‐TA/MAT. Microfilaments were well preserved with good contrast and little evidence of breakage. Although GA as the initial fixative gave good organelle preservation, Os pretreatment was required to prevent artefactual changes in plasmodial strand morphology. The several fixation procedures tested gave pronounced differences in mitochondrial appearance, in some cases giving a negative stained appearance to the cristae. Some advantages in interpretation may result from such reversed contrast. The high contrast and range of densities achieved following the Os/GA‐TA/MAT schedule permitted routine use of thin (silver‐grey) sections, thereby potentially increasing the resolution.