In a cruel experiment conducted by researchers at Imperial College London, a ‘window’ was created in the skulls of live mice so that they could see whether damaged brain cells were regenerating up to one year later.

Over 50 young and adult mice were anesthetised before their heads were shaved and opened up to expose their skulls. Using a dental drill, the researchers drilled a circular groove into the animals’ skull before fixing a glass pane over the holes to create a ‘window’ into the brain which was glued into place with dental cement.

Two weeks later the mice were then subjected to another surgery where lasers were used to damage cells inside their brains. Over the remainder of their life they were then forced to endure multiple, lengthy imaging sessions strapped underneath special microscopes so that the researchers could observe the  regrowth of damaged cells through the ‘windows’ created in their skulls. Each imaging session lasted 60-90 minutes and the anesthetised animals had to be maintained with eye lubricants, heating pads and rehydration solutions to prevent them from developing complications or dying during the procedure.

The mice were killed one, three, six or 12 months after the brain damage surgeries or when “the health of the mouse became compromised”. Whilst under their last anaesthetic they were literally pickled alive and their brains dissected out for analysis. The researchers found that the brain cells were remarkably slow to repair themselves, something that they admit was already widely known about the brain.

During the BUAV recent investigation at Imperial College, animals were found to be suffering more than necessary during experiments and many died because of staff incompetence and neglect.


  1. In vivo single neuron axotomy triggers axon regeneration to restore synaptic density in specific cortical circuits. (2013). Nature Communications, 4: 2038. Article can be found here: