Turbellaria are aquatic worms with the prominent feature that when they are dissected, each one of the two parts is able to regenerate a whole new animal. They are able to regenerate all tissues from the muscle to the intestines, and even the nervous system.

The most representative species of Turbellaria is Dugesia subtentaculata and they are phylogenetically at the origin of flatworms and bilateral animals (in fact they are considered the most primitive bilateral animals). The study of their origin presents the difficulty that there are no fossils because their body is soft. Therefore, the current hypothesis states that its origin is found in a larval form of Cnidaria hydrozoa that kept this genetic and histological condition by blocking the mechanisms of differentiation in adult individuals, which would explain its ability to regenerate tissues and organs.

In the regeneration process there are two types of cells involved: rabdits and neoblasts . The first ones are epithelial secretory cells and protect the wound with a mucous secretion that contains immunity substances, below which a transparent and provisional epithelium called blastema is built. To this blastema, from the rest of the body where they constitute 30% of all tissues, migrate the neoblasts. Neoblasts are indeed stem cells of about 10 um with nucleus, ribosomes and mitochondria, which are capable of producing  the new tissues by differentiation.

However, the mechanism of organ regeneration is not unspecific. The most recent studies of Dr. Aboobaker teams from the University of Nottingham and studies of Drs. Peter Reddien and Christian Petersen from the Whitehead Institute indicate that Turbellaria mantain intact telomers (See Veterinaria Digital, Divulgation Blog # 12 of April 11th 2011 ) as well as having two genes (smed – Bcatetin and Wnt) and the secretion of a growth factor for fibroblasts of brain lymph node, which are expressed differently depending on where in the body has the wound been produced, being able to give, consequently, different types of cells , according to the needs of the wounded individual, including the nervous system.