• mouse;
  • parietal yolk sac;
  • Reichert's membrane;
  • collagenase type IV;
  • dispase


Crucial aspects of axial development in mice occur at early postimplantation stages from the time of implantation to the appearance of the primitive streak. However, this period of development is notoriously refractory to experimental approaches due to the small size of the conceptus and to the presence of the parietal yolk sac, a protective tripartite membrane that surrounds the developing egg cylinder. Here, we describe a method that combines enzymatic digestion and mechanical manipulation to remove the parietal yolk sac of conceptuses at stages between 5.5 and 6.5 days post coitum. This method, which is compatible with whole-mount in situ hybridization and immunostaining techniques, offers a significant improvement over conventional dissection techniques, and it will greatly facilitate research in early mammalian development. Developmental Dynamics 236:489–493, 2007. © 2006 Wiley-Liss, Inc.