part_of part of is part of part of develops from primordium embryonic structure mesenchyme mesoderm-derived structure splanchnic layer of lateral plate mesoderm embryonic tissue dorsal mesogastrium spleen primordium A dense syncitial-like mesenchymal thickening in the dorsal mesogastrium[ISBN]. the embryonic connective tissue made up of loosely aggregated mesenchymal cells, supported by interlaminar jelly, that gives rise to the developing spleen[MP]. splenic primordium EHDAA2:0001904 uberon splenic mesenchyme UBERON:0006293 check difference between splenic and spleen in EMAPA; note that in EHDAA2 the class 'spleen' refers to the mesenchyme EHDAA:3003 UBERON:0009750 left spleen primordium XAO:0000326 spleen mesenchyme EMAPA:18535