Autoradiography

Definition

A technique for visualizing the distribution of radioisotopes within a specimen by apposing the sample to photographic film, nuclear emulsion, or a digital phosphorimaging detector. Decay emissions from the incorporated label expose the detector, producing a spatial map of radioactive concentration. The auto- prefix distinguishes it from techniques using external radiation sources. In entomology, autoradiography enables tracking of labeled compounds—such as insecticides, pheromones, nutrients, or metabolic precursors—through tissues, whole organisms, or ecological samples at resolutions ranging from gross organ level to cellular (micro-autoradiography).

Etymology

From Greek autos (self) + radiography (radiation imaging), indicating the radiation source is internal to the sample

Example

Researchers used whole-body autoradiography to trace the tissue distribution of a radiolabeled juvenile hormone analog in adult crickets, revealing selective accumulation in the fat body and ovaries; micro-autoradiography of the midgut localized silver grains to epithelial cells, confirming active transport rather than passive diffusion.

Synonyms

• radioautography

Related Terms

• isotope labeling
• scintillation counting
• thin-layer chromatography
• metabolism
• pharmacokinetics
• histology
• microscopy

Usage Notes

Micro-autoradiography (cellular resolution) requires coating tissue sections with liquid nuclear emulsion and microscopic examination of developed silver grains. Quantitative autoradiography demands careful calibration against standards of known radioactivity. The technique has largely been supplanted by phosphorimaging for sensitivity and linear dynamic range, though film remains useful for high-resolution anatomical correlation. Contrast with historadiography/microradiography, where the sample is irradiated by an external X-ray source.