Correct option is A
Correct Answer: (a)
Explanation: After limb amputation in newts, the wound surface is rapidly covered by a specialized wound epidermis. This is followed by remodelling of the extracellular matrix, which allows dedifferentiation of underlying cells. These cells then accumulate beneath the wound epidermis to form a blastema, a mass of proliferating progenitor cells. Finally, blastema cells differentiate to regenerate the missing limb structures.
Information Booster
· Newts are classic model organisms for studying vertebrate regeneration.
· The wound epidermis is essential for signaling and blastema formation.
· Extracellular matrix remodelling enables cell migration and dedifferentiation.
· The blastema contains multipotent progenitor cells.
· Proper spatial and positional cues guide differentiation during regeneration.
Additional Knowledge
Incorrect options either place blastema formation before wound epidermis formation or delay epidermal covering until later stages, both of which contradict experimental observations. Without early wound epidermis formation, blastema development does not occur. Similarly, differentiation is always the final step of regeneration, occurring only after blastema formation and growth. This ordered sequence is critical for successful limb regeneration in amphibians.
