Abstract
<title>Abstract</title> <p> The adrenal gland, essential for survival, contains the medulla and cortex. Chromaffin cells (ChrCs) in the adrenal medulla control the fight-or-flight response by releasing catecholamines like epinephrine and norepinephrine. Recent findings reveal that ChrCs originate from two progenitors: 20% from developmentally early, neural crest-derived sympathoadrenal progenitors (SAPs) and 80% from the later Schwann cell precursors (SCPs). We generated functional adrenomedullary organoids from human pluripotent stem cells (hPSCs) via both pathways and in mixed (20% SAP, 80% SCP-derived) cultures. When implanted into chicken embryos, the organoids migrated and integrated into the adrenal gland anlagen. <italic>In vitro</italic> , they released norepinephrine and epinephrine in response to stimulation. Single-cell transcriptomics confirmed developmental trajectories matching human fetal data and allowed the identification of a novel ChrC subtype specifically derived from the SAP that may be responsible for mediating the severe stress reaction via EPI. Assessing developmental knowledge in this human system, we found that SAPs differentiated into ChrCs, but not sympathetic neurons or Schwann cells, showing limited plasticity. Meanwhile, SCPs could produce various cell types but not sympathetic neurons. Furthermore, our work reveals that under stress conditions, SAP-derived ChrCs mainly release epinephrine, while SCP-derived ChrCs release norepinephrine, highlighting distinct functions based on developmental origin. These organoids provide valuable models for studying ChrC development, interactions, and adrenal pathologies. </p>