Practice question

The vitelline envelope is an extracellular coat deposited around growing oocyte by follicle cells and oocyte itself, composed primarily of sulfated and non-sulfated glycoproteins homologous to mammalian zona pellucida proteins ZP1, ZP2, ZP3 equivalents. In sea urchins it includes large molecular weight glycoproteins bearing EBR1 receptor with oligosaccharide chains conferring species-specificity for bindin recognition. Matrix lacks bulk lipids, genomic nucleic acids, or regulatory microRNAs; integrity depends on disulfide crosslinks and carbohydrate-carbohydrate interactions. During slow block, serine protease clips receptors and ovoperoxidase crosslinks glycoproteins to form hardened fertilization envelope.