Hematopoietic stem cells (HSCs) are instrumental for organismal survival as they are responsible for lifelong production of mature blood lineages in homeostasis and response to external stress. To fulfill their function, HSCs rely on reciprocal interactions with specialized tissue microenvironments, termed HSC niches. From embryonic development to advanced aging, HSCs transition through several hematopoietic organs where they are supported by distinct extrinsic cues. Here, we describe …