part of part of surrounds surrounds Rodentia organ part periarterial lymphatic sheath inner periarterial lymphatic sheath of spleen outer periarterial lymphatic sheath of spleen 2026-05-26T00:00:00Z https://github.com/obophenotype/uberon/pull/3722 peripheral PALS UBERON:8930194 outer PALS Inner/outer PALS subdivision is described in rat and mouse (Veerman & van Ewijk 1975, doi:10.1007/BF00225103). In adult human spleen the T-cell regions are discontinuous and lack rodent-type PALS architecture (van Krieken et al. 1985, doi:10.1111/j.1365-2559.1985.tb02841.x; Steiniger, Rüttinger & Barth 2003, doi:10.1177/002215540305100511); no inner/outer subdivision has been demonstrated in humans. dragon-ai-agent The peripheral region of the periarterial lymphatic sheath of the spleen, surrounding the inner periarterial lymphatic sheath of spleen, in which reticulum cells are arranged in cylindrical shells. It contains both T and B lymphocytes and is a site of T-B cell interaction and of antigen-induced B cell proliferation and early plasmablast development, from where plasmablasts migrate towards the red pulp.