We emphasize the ability for bridge and atomic sketch integration to identify and characterize rare cell populations, including AXL+ SIGLEC6+ dendritic cells and pulmonary ionocytes. Single cell transcriptome profiling played an essential role in the initial discovery of these cell types, but a deeper understanding of their biological role and function will benefit from multimodal characterization. The goal of moving beyond an initial taxonomic classification of cell types towards a complete multimodal reference will not be accomplished with a single experiment or technology. We envision that computational tools for cross-modality integration will play key contributions to the construction of this map.
