Regeneration Flashcards
What is epimorphosis regeneration?
- Epimorphosis regeneration requires both re-patterning, de-differentiation, and new growth.
- It is exemplified by amphibian limb regeneration
What is the key step in epimorphosis regeneration?
- formation of a blastema, which consists of cells from under the epidermis that lose their differentiation, enter rapid proliferation, and undergo re-differentiation
What is required for epimorphosis regeneration to occur in amphibian limb regeneration?
- Nervous innervation in the limb provides growth signals (e.g., FGF) necessary for blastema formation.
- FGF10 is required for limb growth but not for de-differentiation
What are the four tissue types that need to be rebuilt during epimorphosis regeneration?
The dermis (skeleton),
muscle,
epidermis,
and Schwann cells.
What information does the blastema contain during epimorphosis regeneration?
- blastema contains proximal-distal positional information, provided by the secretion of retinoic acid (RA) in a morphogen gradient
How does the blastema differentiate into specific identities during epimorphosis regeneration?
- blastema differentiates into specific identities from signals provided by the reformed apical ectodermal ridge (AER).
How does insect leg regeneration differ from amphibian limb regeneration?
- In insect leg regeneration, the process depends on cell-cell interactions
What is specialized epimorphosis?
- Specialized epimorphosis refers to regeneration that occurs only from existing stem cells without full epimorphosis, as seen in certain regeneration processes
What is morphallaxis regeneration?
- requires re-patterning of existing tissue and cell de-differentiation without new growth
- New structures are formed through cell recruitment, not local proliferation.
How does regeneration occur in Hydra?
(small, freshwater, tubular organism belonging to the phylum Cnidaria)
- When Hydra cut, attractive signals are released, leading to the de-differentiation of cells.
- The missing positional information is read by a gradient (antero-posterior gradient), which helps in producing the missing structure
How does regeneration occur in flatworms?
- Flatworms have neoblasts (adult stem cells) that are pluripotent and constantly divide.
- Neoblasts close to the cut differentiate into cells to replace the missing parts
What is the role of Wnt/β-catenin signaling in flatworm regeneration?
- Wnt/β-catenin signaling re-programs cell identity along the antero-posterior axis.
- It is higher in the head and lower in the tail, contributing to the proper patterning during regeneration
what are the two main types of regeneration in higher vertebrates?
The two main types are regeneration from multipotent stem cells and unipotent stem cells
What do multipotent stem cells give rise to during regeneration?
- Multipotent stem cells can give rise to few cells & differentiate into multiple cell types required for tissue repair.
How do unipotent stem cells contribute to liver regeneration?
- Unipotent stem cells in the liver can differentiate into a single cell type and help in tissue repair
