Regeneration of Hydra from Reaggregated Cells

The Hydra model: disclosing an apoptosis-driven generator of Wnt-based regeneration

“…BrdU-positive cells were detected here after a 2 hours labeling. B) The various developmental potentials available in the adult polyp: Upon regular feeding, the animals undergo asexual reproduction through budding; as initially reported by A. Trembley (1744) 5 , they regenerate any missing part after bisection of the body column performed at any level, and, as discovered more recently, these animals can also regenerate after tissue dissociation and reaggregation of the cells 40 . Finally, sexual development takes over when natural conditions (feeding, temperature) become too severe: the parental polyps before dying produce embryos that are protected by a thick cuticle.…”

“…That the Hydra model system is highly amenable to address this question is supported by the vast cellular knowledge based on transplantation, cell-lineage and quantitative cellular analyses that has been accumulated over the past 40 years 8,12,[40][41][42][43][44][45] . These studies identified the differentiation pathways of most cell types in homeostatic and regenerative conditions.…”

Entre homéostasie et développement, quelles stratégies pour régénérer ?

“…Par ailleurs l'amputation de sa colonne corporelle à n'importe quel niveau induit un processus de régénération. Comme dans plusieurs espèces d'hydrozoaires, le processus de régénération peut même démarrer à partir de cellules réagrégées obtenues après dissociation hyperosmotique des tissus (Noda, 1971;Gierer et al, 1972). Plus banalement, le développement sexué est activé lorsque les conditions environnantes deviennent défavorables, telles la baisse de température et de lumière à l'automne ou la diminution de nourriture.…”

Sorting Things Out: Cell Sorting during Hydra Regeneration

“…Hydra, a fascinating freshwater cnidarian famous for being able to regenerate fully after having been dissociated into single cells and recombined into a heterogeneous aggregate (1), plays an important role in our understanding of the process of cell sorting (2,3). Cell sorting describes the phenomenon where a mixed population of cells spontaneously sorts into distinct tissues, and a crucial early step of Hydra regeneration is that the initially heterogeneous aggregate of cells spontaneously sorts into a sphere-within-a-sphere structure with ectodermal cells on the outside and endodermal cells within (see Fig.…”