CCL21 and hematocrit: Although all ECs in HEVs highly expressed the ACKR1, only part of them were surrounded by myofibroblasts (double-positive for ACTA2 and CCL21, Fig. 5a), which were distributed on the adventitia of HEVs (Fig. 4e) or CCL21+ fibroblasts (F1, Fig. 5a) that appeared abundantly around lymphocyte aggregates in thyroid tissues of HT patients (Figs. 4a, d, e and 5b).