Jellyfish, along with other cnidarians such as corals and sea anemones, exhibit high regeneration abilities, but how they form the critical blastema has remained a mystery until now.

A research team based in Japan has revealed that stem-like proliferative cells—which are actively growing and dividing but not yet differentiating into specific cell types—appear at the site of injury and help form the blastema.

The findings were published in PLOS Biology.

"Importantly, these stem-like proliferative cells in blastema are different from the resident stem cells localized in the tentacle," said corresponding author Yuichiro Nakajima, lecturer at the Graduate School of Pharmaceutical Sciences at the University of Tokyo. "Repair-specific proliferative cells mainly contribute to the epithelium—the thin outer layer—of the newly formed tentacle."

According to Nakajima, the resident stem cells that exist in and near the tentacle are responsible for generating all cellular lineages during homeostasis and regeneration, meaning they maintain and repair whatever cells are needed during the jellyfish's lifetime. Repair-specific proliferative cells only appear at the time of injury.