Ligand for members of the frizzled family of seven transmembrane receptors (Probable). Functions in the canonical Wnt signaling pathway that results in activation of transcription factors of the TCF/LEF family (PubMed:20093360, PubMed:21244856, PubMed:24841207, PubMed:26902720). Required for normal embryonic mesoderm development and formation of caudal somites. Required for normal morphogenesis of the developing neural tube (By similarity). Mediates self-renewal of the stem cells at the bottom on intestinal crypts (in vitro) (PubMed:26902720). {ECO:0000250|UniProtKB:P27467, ECO:0000269|PubMed:20093360, ECO:0000269|PubMed:21244856, ECO:0000269|PubMed:24841207, ECO:0000269|PubMed:26902720, ECO:0000305}. This is the function of WNT3A (Wnt family member 3A, ENSG00000154342).