Researchers at the Tufts Center for Regenerative & Developmental Biology at Tufts University are testing whether a replicated amniotic (womb fluid) environment can promote limb regeneration in adult mammals.

They’ve developed a small, cylindrical “regenerative sleeve” that can be filled with an aqueous solution and fastened onto the stump of a rat’s amputated limb. The sleeve is fitted with a variety of ports and electrical connections, so the researchers can sample and alter the container’s chemical contents and also control ion flows and voltage gradients that might affect 
regeneration.