Diseases and Management of Crops under Protected Cultivation

(Diseases and Management of Crops under Protected Cultivation)
Polymerization
Keep the specimen at 40-50°C for overnight for better penetration of the resin and then increase
the temperature to 60°C for 24-48 hrs so that the resin gets hardened.
Removing the Blocks from the mould
After polymerization the blocks can be easily removed.
ULTRAMICROTOMY
Glass knife is used for cutting ultrathin sections. Ultrathin sections show interference colors while
floating on the liquid of the trough. This makes it possible to determine the thickness of the
sections.
Gray-60 nm (600A0 ); optimal for high resolution work.
Silver- 60-90 nm; ideal for most of the purposes.
Gold- 90-150 nm; useful for low magnification and autoradiography.
Purple ,blue,green and yellow- range from 150-320nm; very thick sections and not suitable for
transmission microscopy.
He sections are picked on to the grids to be observed in the TEM
Tem Observations
One of the most important tasks is learning to distinguish normal from abnormal tissues. In
order to successfully interpret an electron microscopic (EM) case, you need some of basic tools
such as a working knowledge of normal. To describe a micrograph:
Begin by stating which tissue(s) is (are) present
Brief description of normal landmarks present
Describe pathologic changes
Have good vocabulary of EM terms - appendix I in the 2nd edition of cell pathology by
Cheville has a glossary of EM terms; this is a good starting point.
Morphologic diagnosis
Same rules apply as for LM cases
Be concise
Example: hepatocyte: degeneration, diffuse, moderate with intranuclear virions.
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