The yolk membrane of fish, amphibians, birds and other animals has been clearly concluded that it refers to the non-cellular structure composed of glycoprotein between oocytes and follicular cells, which belongs to the primary egg membrane and cannot be classified as cell membrane.

Mammals have no yolk membrane, and the "oocyte membrane" in some textbooks, papers and monographs actually refers to the oocyte membrane, which can indeed be classified as cell membrane.