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#regenerative biology

3 public questions tagged with this topic.

Regeneration -l

Which of the following organisms can regenerate a lens in their eye?

Lens regeneration classic example of Wolffian transdifferentiation first described in urodeles where dorsal iris pigment epithelial cells dedifferentiate, lose melanin, re-enter cell cycle, and differentiate into transparent lens expressing crystallins. This requires retinal signals including FGF2, retinoic acid, and reactivation of Pax6. Mammals and birds possess insufficient plasticity exhibiting only capsular cataract healing, while Hydra regenerates photoreceptive structures but true lens paradigm remains amphibian. Although provided key lists Hydra as answer, textbook developmental model for functional lens regeneration remains adult newt Notophthalmus viridescens demonstrating cellular reprogramming potential relevant to regenerative medicine and stem cell induced transdifferentiation studies.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 19: Lens regeneration via transdifferentiation - amphibian Wolffian regeneration.

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Regeneration -l

Which of the following organisms exhibits near-total regeneration ability?

Hydra, freshwater cnidarian with diploblastic body and simple nerve net, epitomizes near-total regeneration due to perpetual activity of three stem cell lineages: ectodermal epithelial, endodermal epithelial, and interstitial multipotent stem cells capable of producing neurons, nematocytes, and gametes. Small fragments containing few hundred cells reorganize polarity and reform head with hypostome organizer and basal disc within days without scarring. Zebrafish regenerate selected organs, mammals and birds show limited repair due to fibrotic responses. Hydra's continuous Wnt3-driven head organizer activity and absence of complex adaptive immunity enable whole-body reconstitution from minimal tissue.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 19: Hydra model - interstitial stem cells and near-total regeneration.

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Cancer

Normal stem cells maintain tissues mainly by

Self-renewal and differentiation, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)

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