The process of transporting polymeric IgA and polymeric IgM immunoglobulin, via transcytosis mediated by the polymeric immunoglobulin receptor (pIgR), from the basolateral surface to apical surface of an epithelial cell. At the apical surface the immunoglobulin binding portion of the pIgRis cleaved and remains bound to the transported immunoglobulin as secretory component (SC). The same process is used for the transport and excretion of IgA immune complexes to the luminal surface of the mucosa.