The problem. Imaging methods like MERFISH give single-molecule resolution but on targeted panels; capture methods give whole-transcriptome coverage but coarse resolution. The obvious wish is both — thousands of genes and subcellular precision. The obstacle is optical crowding: image ten thousand genes at once and the fluorescent spots overlap into an unreadable blur.

The idea. seqFISH+ beats the crowding limit by spreading signals across many more pseudocolours read out over sequential rounds, so at any instant only a sparse subset of molecules fluoresces and spots stay separable. Combined with super-resolution, this scales in-situ imaging toward the whole transcriptome (~10,000 genes) while keeping single-molecule, subcellular localisation.

Why it matters. This directly addresses the core spatial trade-off from MERFISH — resolution versus breadth — by attacking the physical bottleneck (crowding) rather than accepting it. For the STU’s evaluation of platforms, seqFISH+ marks how far the imaging branch can push toward transcriptome scale, and what it costs (imaging rounds, time, complexity). It’s the ambitious end of imaging-based spatial.

Verdict. Foundational as a proof that imaging can approach transcriptome scale; throughput and complexity keep it more a research method than a routine platform. Read it as the “have it both ways” attempt on the spatial spectrum — and the context for why commercial platforms still choose targeted panels.