Chemokine CXCL13 is essential for lymph node initiation and is induced by retinoic acid and neuronal stimulation
The location of embryonic lymph node development is determined by the initial clustering of lymphoid tissue-inducer (LTi) cells. Here we demonstrate that both the chemokine CXCL13 and the chemokine CCL21 attracted LTi cells at embryonic days 12.5-14.5 and that initial clustering depended exclusively on CXCL13. Retinoic acid (RA) induced early CXCL13 expression in stromal organizer cells independen