part_of part of part of has part has part has_part bounding layer of bounding layer of material entity material entity glycoprotein oocyte zona pellucida http://upload.wikimedia.org/wikipedia/commons/8/81/Gray3.png UBERON:0000086 oolemma uberon vitelline membrane ZFA:0001111 BTO:0003135 pellucid zone EHDAA2:0002220 EMAPA:16035 EHDAA:31 striated membrane zona striata Outside the plasma membrane, three envelopes surround the ovum. The first, the primary egg envelope, lies between the plasma membrane and the surrounding cells of the ovary. The most consistent component of this primary layer is the vitelline membrane, a transparent jacket of fibrous protein. In mammals, the homologous structure is called the zona pellucida.[well established][VHOG] A glycoprotein membrane surrounding the plasma membrane of an oocyte. It is a vital constitutive part of the latter, external but not extraneous to it. The zona pellucida first appears in multilaminar primary oocytes. zona pellucida - vitelline membrane UMLS:C0043519 GAID:410 NCIT:C33896 zona radiata TAO:0001111 FMA:18674 MESH:D015044 VHOG:0000720 MA:0001715 Wikipedia:Zona_pellucida EHDAA:62 vitelline envelope acellular anatomical structure ovary