Rosette morphology in zona glomerulosa formation and function.

How morphology informs function is a fundamental biological question. Here, we review the morphological features of the adrenal zona glomerulosa (zG), highlighting recent cellular and molecular discoveries that govern its formation. The zG consists of glomeruli enwrapped in a Laminin-β1-enriched basement membrane (BM). Within each glomerulus, zG cells are organized as rosettes, a multicellular structure widely used throughout development to mediate epithelial remodeling, but not often found in healthy adult tissues. Rosettes arise by constriction at a common cellular contact point mediated/facilitated by adherens junctions (AJs). In mice, small, dispersed AJs first appear postnatally and enrich along the entire cell-cell contact around 10 days after birth. Subsequently, these AJ-rich contacts contract, allowing rosettes to form. Concurrently, flat sheet-like domains in the nascent zG, undergo invagination and folding, gradually giving rise to the compact round glomeruli that comprise the adult zG. How these structures impact adrenal function is discussed.