Fertilisation

• acrosome reaction

  1. sperm swims to egg
  2. Acrosome if sperm releases digestive enzymes which breakdown follicle cells and the zona pellucida
• cortical reaction

  1. Egg cell releases contents of vesicles (and fuses with the membrane) Known as granules, into space between egg cell membrane and zona pellucida
  2. releasing enzymes by exocytosis , this thickens and hardens the sons pellucida preventing polyspermy