Welcome to the February 2026 In focus in HCB editorial. In this editorial we will highlight one recent manuscript utilizing the power of spatial transcriptomics to uncover conserved canonical marker genes in human and mouse adrenal glands.

In 2020 Nature Methods proclaimed “spatially resolved transcriptomics” their Method of the Year (Focus Editorial 2021). Their rationale for this choice was predicated on the premise that “these methods are able to elucidate single-cell heterogeneity and define cell types while also retaining spatial information.” Indeed, the ability to map cellular transcripts in the context of the spatial organization of a tissue is critical for the understanding of cell–cell interactions and cell biological processes in both health and disease. While many iterations of spatial transcriptomics instrumentation exist, there are several key differences between the technologies, including (1) method of transcript detection; (2) resolution (near cellular, cellular, and subcellular); (3) number of different transcripts detected (whole transcriptome versus limited transcripts, typically around 5000); (4) species for which probe sets exist; (5) ability to use paraffin sections, cryosections, or both; and (6) area available on slide for tissue section placement and subsequent spatial analysis. This list is far from exhaustive, and these technologies and innovations are advancing at break-neck speed (see, for instance, Grases and Porta-Parda 2025; Ozirmak Lemi et al. 2025; Shi et al. 2025 for more comprehensive reviews of the technologies). Spatial transcriptomics has been especially utilized in cancer biology research, often emphasizing the tumor microenvironment together with the tumor itself (Shi et al. 2025). Now, in a different area of application, Blatkiewicz and colleagues (2026) have used spatial transcriptomics to assess the gene expression profile across the adrenal glands of humans and mice, with the stated goal of identifying canonical marker genes conserved between the two species to determine whether the mouse represents an appropriate model to investigate human adrenal diseases. Indeed, over the years, much debate has been focused on the relevance of animal models (particularly rodents) to serve as surrogates for studying human diseases, and especially therapeutic treatments (Bruter et al. 2024; Pera et al. 2024). Comparing gene expression profiles within the same region of an organ or tissue from humans and rodents in a spatially determined manner would provide strong supporting evidence for justifying the physiological relevance of the animal model for studying human disease.

In their very detailed investigation, Blatkiewicz and colleagues (2026) employed 10× Genomics Visium spatial transcriptomics to search for canonical marker genes present in distinct anatomical locations within the adrenal cortex and medulla from one human sample (cryosections) and four mouse samples (paraffin sections). The adrenal gland consists of two main parts: (1) the cortex and (2) the medulla, which is composed of adrenaline- and noradrenaline-secreting chromaffin cells. The cortex is subdivided into three distinct zones on the basis of histology and secretory function—the zona glomerulosa (ZG), the thin outermost layer, which primarily produces mineralocorticoids; the zona fasciculata (ZF), the thicker middle layer, which produces glucocorticoids; and the zona reticularis (ZR), the inner layer, which produces androgens; in mice, however, the ZR is lacking and represented by an ill-defined transient X-zone (ZX). Since the zones have distinct functions and morphology, as just briefly mentioned, this should be revealed in the marker genes identified within them. As with all spatial transcriptomic studies, voluminous amounts of data are produced and analyzed via various software paradigms, and we encourage the reader to consult the manuscript for the full details. The following is a brief summary of some of their key results and findings regarding conserved canonical marker genes identified in each region of the adrenal gland for both species: (1) beginning with the cortical zones, they identified 62 conserved genes in the ZG, including CYP11B2 for aldosterone synthase; (2) 7 conserved genes in the ZF, mostly representing glucocorticoid production; (3) 18 conserved genes in the ZR (human)/ZX (mouse), many related to metabolic transcription (quite interesting since this similar function exists in a region that is histologically different between human and mouse); and (4) a whopping 697 conserved genes expressed in the medulla, mostly related to neuroendocrine identity and catecholamine biosynthesis. The importance of this manuscript relates to its creation of the first cross-species spatial transcriptomic atlas of the adrenal gland. By locating and defining conserved adrenal zone-specific canonical gene markers, it enhances the translational relevance of mouse adrenal gland studies and provides novel tools for further research into adrenal development, physiology, and pathology.