Lymph node (LN) stromal cells play a crucial role in LN development and in supporting adaptive immune responses. However, their origin, differentiation pathways, and transcriptional programs are still elusive. Here, we used lineage-tracing approaches and single-cell transcriptome analyses to determine origin, transcriptional profile, and composition of LN stromal and endothelial progenitors. Our results showed that all major stromal cell subsets and a large proportion of blood endothelial cells originate from embryonic Hoxb6⁺ progenitors of the lateral plate mesoderm (LPM), whereas lymphatic endothelial cells arise from Pax3⁺ progenitors of the paraxial mesoderm (PXM). Single-cell RNA sequencing revealed the existence of different Cd34⁺ and Cxcl13⁺ stromal cell subsets and showed that embryonic LNs contain proliferating progenitors possibly representing the amplifying populations for terminally differentiated cells. Taken together, our work identifies the earliest embryonic sources of LN stromal and endothelial cells and demonstrates that stromal diversity begins already during LN development.

淋巴结 (LN) 基质细胞在 LN 发育和支持适应性免疫反应中起着至关重要的作用。然而，它们的起源、分化途径和转录程序仍然难以捉摸。在这里，我们使用谱系追踪方法和单细胞转录组分析来确定 LN 基质和内皮祖细胞的起源、转录谱和组成。我们的研究结果表明，所有主要的基质细胞亚群和大部分血液内皮细胞都来自胚胎 Hoxb6 ⁺侧板中胚层 (LPM) 祖细胞，而淋巴管内皮细胞来自 Pax3 ⁺中胚层旁祖细胞 (PXM)。单细胞 RNA 测序揭示了不同的 Cd34 ⁺和 Cxcl13的存在⁺基质细胞亚群，并表明胚胎 LNs 含有增殖的祖细胞，可能代表终末分化细胞的扩增群体。总之，我们的工作确定了 LN 基质和内皮细胞的最早胚胎来源，并证明基质多样性已经在 LN 发育过程中开始。