Single-cell spatial transcriptomics reveals sex-dependent gene expression and intercellular signaling in the mouse adrenal cortex

The female-predominant X-zone, a transient cortical structure recognized for nearly a century, has lacked comprehensive molecular characterization. Here we use high-resolution Visium HD spatial transcriptomics with Cellpose-based cell segmentation to generate ~203,000 near-single-cell-resolution transcriptomic profiles from sexually mature mouse adrenal glands (four male, four female).

We identify ten distinct cell populations with sex differences spatially restricted to inner cortical zones. The X-zone exhibits pronounced sexual dimorphism, with Akr1c18 (20α-hydroxysteroid dehydrogenase) as the definitive marker (log₂FC = −16.28, female-enriched), establishing the X-zone as a specialized progesterone-catabolizing endocrine compartment. Female adrenal glands exhibit greater intercellular communication complexity (435 vs 369 interactions) and higher aggregate signalling strength, with SPP1-integrin pathways enriched in the female X-zone microenvironment.