Investigating a Zebrafish Larval Brain Injury Using Large-Scale Scanning Transmission Electron Microscopy

Take resin-embedded, chemically fixed ultrathin brain sections from healthy and brain-injured zebrafish larvae mounted on a one-hole grid. 

The sections are stained with heavy metals to enhance image contrast during microscopic imaging.

Place the grid in a sample holder and transfer the holder to the microscopy chamber.

Align the grid under the electron gun, which generates an electron beam.

An array of electromagnetic lenses and coils focuses the electron beam onto the sections.

Move the sample holder to scan the sections in a raster pattern.

As the electron beam passes through the tissue sections, the stained electron-dense regions scatter more electrons, while the unstained regions transmit the electrons.

The detector collects these electron signals, creating high-resolution brain images.

Compared to the control, the injured brain shows phagocytic microglia containing numerous intracellular inclusions, a characteristic feature of injury-induced neurodegeneration.