Oxygen-free metabolism in the bird inner retina supported by the pecten
Summary
This Nature paper reports that the avian inner retina can sustain an oxygen-independent metabolic state supported by the pecten oculi. Using a combination of spatial transcriptomics, single-cell RNA sequencing, gas measurements, oxygen-diffusion modelling and micro-CT imaging, the authors show anatomical and molecular specialisations that allow birds to maintain retinal function with minimal intraretinal oxygen supply. Key molecular signatures include elevated expression of glucose and monocarboxylate transporters in Müller glia and prominent expression of metabolic transporters and carbonic anhydrase in the pecten/conus structure. The study provides extensive datasets and supplementary models to back the conclusions.
Key Points
- Evidence that the bird inner retina can operate with very low oxygen availability, relying on alternative (oxygen-independent) metabolism.
- The pecten oculi (and reptilian conus papillaris) shows gene-expression signatures (GLUT1, MCT1, CA4) consistent with supplying metabolites/transport to the neural retina.
- Spatial transcriptomics and single-cell RNA-seq (zebra finch atlas) identify high GLUT1 and MCT1 expression in Müller glia, suggesting metabolite shuttling roles.
- Micro-CT imaging and vascular casts reveal the pecten’s large surface area and arterial supply that supports ocular metabolite/flux exchange.
- In vivo oxygen profiling and finite-element diffusion modelling estimate retinal oxygen consumption and flux from choroid and pecten, supporting the functional claim.
- Extensive data availability: raw/spatial/scRNA-seq datasets on GEO, imaging on Figshare, and rich supplementary material (models, peer-review files).
Content summary
The authors combine multi-modal approaches to show that bird retinas are adapted to a low-intraretinal-oxygen regime. Molecular data (spatial and single-cell) indicate that Müller glia express transporters suited for glucose and monocarboxylate uptake, while the pecten expresses transporter and enzyme genes that would enable it to act as a metabolic support organ. Anatomical imaging documents the pecten’s structure and vascular supply, and oxygen micro-profiles plus diffusion modelling quantify how oxygen and metabolic fluxes are partitioned between choroid and pecten. Overall, the data support a model in which the pecten helps the inner retina function with reduced reliance on intraretinal blood vessels.
The paper provides a zebra finch single-cell atlas (40,496 cells), cross-species comparisons (birds, reptiles and multiple vertebrates), and multiple controls (antibody specificity, modelling fits). The authors emphasise evolutionary and functional implications, especially the trade-off between light transmittance and oxygen delivery in retinal design.
Context and relevance
This study addresses a longstanding question in comparative vision biology: how avian eyes reconcile the need for high optical quality with adequate metabolic support. The findings relate directly to the ‘opto-respiratory compromise’—where minimising light-scattering vasculature can limit oxygen delivery—and show a distinct avian solution via the pecten. That has implications for understanding vertebrate retinal evolution, how birds maintain vision under hypoxia (for example at high altitude), and may inform biomedical thinking about retinal metabolism and disease where oxygen supply is limiting.
Why should I read this?
Short version: birds have evolved a clever workaround so their retinas can run on very little oxygen — the pecten acts like a metabolic backstage crew. If you care about how eyes evolved, how tissues handle low-oxygen stress, or want dataset-rich evidence that links structure to metabolism, this is a neat, data-packed read (and we’ve done the skimming for you).
Source
Article Date: 21 January 2026
Article URL: https://www.nature.com/articles/s41586-025-09978-w
Article Image: Figure 1 (Nature)