A comparative review of single-cell atlases: mapping cellular diversity across species and tissues

Abstract Single-cell sequencing (sc-seq) technologies have revolutionized biomedical research by enabling high-resolution analysis of cellular heterogeneity across multiple dimensions, including transcriptomics, epigenomics, and spatial profiling. These advances have led to the development of comprehensive single-cell atlases—reference maps of cell types and states across tissues and organisms, such as the Human Cell Atlas and Mouse Cell Atlas. These resources are foundational frameworks for investigating gene regulation, tissue architecture, and disease mechanisms. However, variations in biological focus, species representation, and dataset scale