Hormone boosts regeneration of amputated limbs in frogs

The video discusses a bioreactor that uses progesterone to promote tissue regeneration, tested on African clawed frogs. The bioreactor, made from silicone and hydrogel, was applied to amputated frog limbs. After 9.5 months, frogs treated with progesterone developed paddle-like structures with bones, nerves, and blood vessels, while untreated frogs grew cartilaginous spikes.

Describe the composition of the gel used in the bioreactor.

What structures did the frogs grow after treatment with the bioreactor?