Eggshell membrane. Coloured scanning electron micrograph (SEM) of the internal membrane from the shell of a hen's egg. Several membranes are found around the embryo in a bird's egg. The shell membranes adhere to the inner surface of the shell, with an air space between them at one end of the egg. Changes in the eggshell as the chick develops permit the passage of carbon dioxide and oxygen and the release of water vapour via the shell membranes. The function of the membranes and the shell is to protect the developing chick from trauma and dessication. Magnification: x1500 at 5x7cm size. x5200 at 10x8"~LANDSCAPE"