Hematopoiesis is the formidably complex and dynamic biological process by which hundreds of billions of blood cellular components are produced on a daily basis. High rates of cell production are sustained by a population of hematopoietic stem and progenitor cells (HSPCs), which are self-renewing and multipotent stem cells, endowed with a remarkable regenerative capacity. In adult individuals, the hematopoietic process takes place in bone marrow tissues, within an intricate infrastructure formed by non hematopoietic, so-called stromal cells, which beyond lending mere structural support, critically regulate hematopoiesis at all levels. In the lab we aim to dissect the cellular make-up of hematopoietic tissues and understand how stromal components interact with blood cells and contribute to the regulation of bone marrow hematopoietic function and hematopoietic stem cell maintenancein health and disease. For this, we have in the past years developed 3D microscopy techniques that allow us to visualize all the tissue components in situ, observe their structural changes and define the spatial affinities between them, which can teach us about their functional crosstalk.