Determinants of postnatal spleen tissue regeneration and organogenesis

Proposed interactions between spleen organiser cells and LTi/B cells which leads to marginal zone remodelling and adult white pulp formation. During late embryogenesis (E16.5), CD4+IL-7Rα+ lymphoid tissue inducer (LTi) cells can be observed between the central arteriole (CA) and presumptive MAdCAM-1+VE-Cadherin+ spleen organiser (SPo) cells.19 After birth, LTi continue to co-localise with SPo (MAdCAM-1+CD31+), which form a primitive marginal zone network surrounding the CD31+ central arterioles.17,20 This postnatal developmental stage coincides with B cell migration into the spleen,17 and both LTi and B cells contribute to lymphotoxin signalling which upregulates MAdCAM-1 expression in the marginal zone, and initiates vascular reorganisation of the Flk-1+ephrinB2+ marginal sinus (MS) network that extends through the white pulp.36 In the adult, MAdCAM-1+CD31+ cells are localised in the marginal zone and represent mature marginal zone reticular cells (MRC