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A day in the (neuroscience) life: Tissue Processing

The researchers in this lab prepare brain tissue for several other teams at the Allen Institute


3 min read

It’s a cold March morning in Seattle, and Windy Ho is waiting for a piece of brain.

He’s been in the lab since 7:00, preparing reagents and tools. The patient’s surgery was scheduled for 7:40, but there were delays. Finally, a small white van pulls into the loading dock in the Allen Institute garage. Michael Clark, who’s also a researcher on the tissue processing team, jumps out of the passenger seat to retrieve the van’s precious cargo.

Mo Hatsabout and Clark unload a wheeling cart from the back of a van in the loading dock of the Allen Institute on Friday, March 11, 2022. The cart contains a small cooler with a tiny piece of human brain nestled inside.

“Y’all ready?” Clark asks. In the tissue processing lab, which the team has affectionately dubbed the bat cave, Clark and Ho have unpacked the cooler from the van, which contains a bottle of clear liquid packed on ice. Floating in the liquid, a special buffer Ho made fresh that morning, is a small blob of tissue, pink and beige.

It’s a still-alive piece of a person’s brain, removed during surgery less than an hour before and donated by the patient to science. In the course of operating to remove a brain tumor, the patient’s surgeon needed to remove a small section of healthy brain to reach their disease. With the patient’s consent, this section of healthy tissue is preserved in liquid and rushed across town to the Allen Institute laboratories.

Clark carefully ladles the tissue chunk out of the bottle and slides it onto a small dish on ice that Ho has prepared. The pair spend several minutes examining and discussing the piece. Their morning task: to mount and slice the tiny piece into even smaller slices, ready for different teams at the Institute to perform experiments on.

Five slices are slated to go to the electrophysiology lab, also known as e-phys, the neuroscientists who capture electrical activity from living neurons using specialized microscope rigs outfitted with tiny electrodes. E-phys gets the best of the best, Clark says. Two slices go to histology, the team that takes images. One slice is to be frozen.

Today, Ho is doing the cutting. He preps the piece of brain in a small blob of agar, a gelatinous substance that stabilizes the brain while it’s being cut. The agar plus brain gets slotted into an automatic slicing machine called a compresstome, which slowly shears incredibly thin slices into a pool of liquid. Ho carefully fishes them out.

Clark keeps track of the slices, watching over his shoulder. The whole thing feels like an incredibly slow and careful process, but it’s actually over within 45 minutes of the brain’s arrival at the building. Ho puts the slices of brain into a warm bath, bringing them back up to body temperature. “It helps them destress,” he says. The cells, still alive, have been through a lot already this morning.

The tissue processing team doesn’t work only on human brains – they process other kinds of brains frequently – but the fresh, human surgical samples are special, they said.


“It’s a bit stressful,” Clark said. “This tissue is so precious, and you want to treat it with as much respect as possible.”

The hardest part of their job? The paperwork, Ho jokes. Their days are generally about half brain-slicing and half data entry. Slicing is by far the more exciting part.

Photos by Erik Dinnel, Senior Producer at the Allen Institute, and text by Rachel Tompa, Senior Editor at the Allen Institute. Get in touch at