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Updated: Jun 17, 2026
Dissection and Immunohistochemistry of Larval, Pupal and Adult Drosophila Retinas
Published on: November 14, 2012
Identification of retinal transformation hot spots in developing Drosophila epithelia
Claire L Salzer1, Justin P Kumar
1Department of Biology, Indiana University, Bloomington, Indiana, United States of America.
Background:
The retinal determination (RD) network is an evolutionarily conserved regulatory circuit that governs early events in the development of eyes throughout the animal kingdom. Ectopic expression of many members of this network leads to the transformation of non-retinal epithelia into eye tissue. An often-overlooked observation is that only particular cell-populations within a handful of tissues are capable of having their primary developmental instructions superseded and overruled.
Methodology/Preliminary Findings:
Here we confirm that indeed, only a discrete number of cell populations within the imaginal discs that give rise to the head, antenna, legs, wings and halteres have the cellular plasticity to have their developmental fates altered. In contrast to previous reports, we find that all transformable cell populations do not lie within the TGFbeta or Hedgehog signaling domains. Additionally neither signaling cascade alone is sufficient for non-retinal cell types to be converted into retinal tissue. The transformation "hot spots" that we have identified appear to coincide with several previously defined transdetermination "weak spots", suggesting that ectopic eye formation is less the result of one network overriding the orders of another, as previously thought, but rather is the physical manifestation of redirecting cell populations of enormous cellular plasticity. We also demonstrate that the initiation of eye formation in non-retinal tissues occurs asynchronously compared to that of the normal eye suggesting that retinal development is not under the control of a global developmental clock.
Conclusions/Significance:
We conclude that the subregions of non-retinal tissues that are capable of supporting eye formation represent specialized cell-populations that have a different level of plasticity than other cells within these tissues and may be the founder cells of each tissue.
Insights
Specific cell populations possess high plasticity, enabling developmental fate alteration for ectopic eye formation. This process is not controlled by a global clock but by redirecting these specialized cells.
Area of Science:
- Developmental biology
- Cellular plasticity
- Gene regulatory networks
Background:
- The retinal determination (RD) network controls early eye development across animals.
- Ectopic expression of RD network genes can transform non-retinal tissues into eye tissue.
- Only specific cell populations exhibit plasticity for developmental fate alteration.
Purpose of the Study:
- To identify and characterize cell populations with developmental plasticity for ectopic eye formation.
- To investigate the signaling pathways involved in overriding developmental instructions.
- To understand the timing and regulation of ectopic eye development.
Main Methods:
- Analysis of cell populations within imaginal discs.
- Investigation of TGF-beta and Hedgehog signaling pathways.
- Comparison of ectopic eye formation timing with normal development.
Main Results:
- Identified discrete cell populations in imaginal discs with high cellular plasticity.
- Found that transformable cell populations are not exclusively within TGF-beta or Hedgehog signaling domains.
- Ectopic eye formation initiation is asynchronous, suggesting no global developmental clock control.
- Transformation "hot spots" correlate with transdetermination "weak spots".
Conclusions:
- Specialized cell populations with unique plasticity support ectopic eye formation.
- These plastic cell populations may represent tissue founder cells.
- Ectopic eye formation results from redirecting inherently plastic cells, not solely network override.
