- In case of morphallactic regeneration:
(1) there is re-patterning of the existing tissues with little new growth
(2) there is re-patteming of the existing tissues after the stem cell division has taken place
(3) there is cell division of the differentiated cells which maintain their differentiated state to
finally form a complete organism.
(4) there is dedifferentiation of the cells at the cut surface which become undifferentiated. These undifferentiated cells then divide to re- differentiate to form the complete structure
Morphallaxis describes a regeneration mechanism where the organism repairs or replaces lost parts primarily by re-patterning and reorganizing existing tissues, rather than by extensive new cell growth or blastema formation. This is a hallmark regenerative strategy in simpler organisms like Hydra.
What Happens During Morphallaxis?
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The existing cells and tissues change position, shape, and function to compensate for lost portions.
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New growth or cell division is minimal or absent early in the regeneration phase, contrasting with processes like epimorphosis.
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The organism’s body plan is restored on a smaller scale but remains functionally complete.
Analysis of the Provided Options
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(1) There is re-patterning of the existing tissues with little new growth:
This option precisely captures the essence of morphallaxis. Existing tissues reorganize with minimal or no new cell proliferation. This description aligns well with regeneration seen in Hydra. -
(2) There is re-patterning of the existing tissues after the stem cell division has taken place:
This implies that significant cell division precedes repatterning, which is more characteristic of epimorphosis rather than morphallaxis. -
(3) There is cell division of the differentiated cells which maintain their differentiated state to finally form a complete organism:
This suggests proliferation without dedifferentiation or repatterning and does not accurately describe morphallaxis. -
(4) There is dedifferentiation of the cells at the cut surface which become undifferentiated. These undifferentiated cells then divide to re-differentiate to form the complete structure:
This is typical of epimorphosis, where a blastema of undifferentiated cells forms and proliferates, so it is not morphallaxis.
Summary
Morphallactic regeneration is best described by the statement indicating repatterning of existing tissues with little new growth. This form of regeneration relies on existing cells reorganizing themselves to restore lost parts efficiently and is exemplified by Hydra and certain simple organisms.
Final Answer:
(1) there is re-patterning of the existing tissues with little new growth -
