Table 1. Cellular sources tangled in regeneration processes of different tissues and organisms.

Cell type	Process	Regenerating tissue/organism	Reference
Interstitial stem cells	Differentiation to zymogen gland cells	Hydra head	107
Zymogen gland cells	Trans-differentiation to granular mucous cells	Hydra head	108
Mesenchymal stem cells/neoblasts	Self-renewal and pluripotent differentiation potential	Lethally irradiated planarians	109, 110
Liver progenitor cells	Differentiation to hepatocytes	Chronic liver injury in mice	77, 78 111
Hepatocytes	Proliferation	Partial hepatectomy in mice	88, 89, 90 111
Cardiomyocytes	Proliferation and differentiation	Damaged heart in zebrafish	112, 113
Pigmented epithelial cells	Dedifferentiation, proliferation and differentiation to lens cells	Lens regeneration in newt	114
Syncytial skeletal myotubes	Dedifferentiation to mononucleate cells that are able to proliferate	Appendage regeneration in urodele	25, 115
Skeletal muscle satellite cells	Activation	Limb regeneration in salamander	116

One of the essential processes underlying tissue regeneration is production of new cells. These new cells can be derived from distinct origins such as amplification and differentiation of resident stem and progenitor cells, proliferation of mature cells, dedifferentiation of cells to a more stem state or trans-differentiation of one cell type to another cell type.¹⁰⁶ In the table above, the different cell types involved in specific regeneration processes are listed