part of part of develops from develops from internal ear endolymphatic sac From the posterior wall of the saccule a canal, the ductus endolymphaticus, is given off; this duct is joined by the ductus utriculosaccularis, and then passes along the aquaeductus vestibuli and ends in a blind pouch, the endolymphatic sac, on the posterior surface of the petrous portion of the temporal bone, where it is in contact with the dura mater. Studies suggest that the endolymphatic duct and endolymphatic sac perform both absorptive and secretory, as well as phagocytic and immunodefensive,functions . [WP,unvetted]. FMA:75639 VHOG:0000791 EHDAA2:0000441 EHDAA:7761 SCTID:279810008 UBERON:0002223 EMAPA:17593 AAO:0000551 Wikipedia:Endolymphatic_sac MESH:D004712 GAID:887 MA:0001188 saccus endolymphaticus endolymphatic appendage inner ear epithelium epithelial sac