The eggshell is the outer covering, 0,2-0,5 mm thick. It consists of two layers: an outer layer, called calcareous or spongy, made up of keratin-collagen fibers with minerals on them-the pigment is present in this layer; and an inner layer, made up of protein granules. The crust has about 8-9 thousand pores, through which gas exchange takes place
Under the shell are two egg membranes (sub-shell and peri-shell), which adhere tightly to each other, except at the blunt end of the egg, where they form a so-called air chamber
The egg white acts as a shielding agent for the yolk. It consists of a thin layer of dense protein surrounding the yolk, a layer of thin protein, and two chalazas (fibrous structures) that hold the yolk in a central position
The egg yolk is a semi-fluid, viscous mass that is light yellow to dark orange (the color depends on the breed of hen and how it is fed). It is covered with vitelline membrane.
