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 .

http://purl.obolibrary.org/obo/UBERON_0002223

FMA:75639

http://en.wikipedia.org/wiki/Endolymphatic_sac

MA:0001188

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 .

endolymphatic sac

UBERON:0002223

endolymphatic sac

http://purl.obolibrary.org/obo/UBERON_0000025