Ultrastructural Analysis of a Mouse Brain Section Using Transmission Electron Microscopy

Take an osmium tetroxide-fixed mouse brain section embedded in a resin block.

Obtain a section image and align it with a pre-prepared atlas image to identify the region of interest.

Mark the borders of this region on the block.

Heat the resin to soften it and excise the marked region.

Glue the specimen to a glass holding bar and trim it.

Using an ultramicrotome, prepare semithin and ultrathin sections.

Transfer the semithin and ultrathin sections onto glass carriers and nickel grids, respectively.

Stain the semithin sections with a dye that binds to nucleic acids, ribosome-rich cytoplasm, and the extracellular matrix.

Wash the sections and examine them under a light microscope to confirm the presence of the target area.

Observe the ultrathin sections under a transmission electron microscope.

Osmium tetroxide enhances the electron density of cellular and organelle membranes, providing high contrast against the less electron-dense cytoplasm, enabling visualization of cellular ultrastructure.