Figure 1 egg structure
1. Plastic protective film 2. Eggshell 3. Egg yolk membrane 4. Ligament layer concentrated protein 5. Inner shell film 6. Air chamber 7. Shell film 8. Ligament 9. Protein concentrate 10. Internal dilution protein 1 1. External dilution protein 12. Egg yolk heart 65438+.
The eggshell is the hard protection of the outermost layer of the egg, which plays a role in protecting the yolk and protein, and can supply the calcium needed for embryo hatching. Eggshell is densely covered with small holes (called pores), through which embryos can exchange gas and metabolize water with the outside world during development. The eggshell surface is also coated with a layer of colloidal mucus (called eggshell outer membrane), which can protect the egg from microbial infection such as bacteria or mold and prevent the water in the egg from evaporating, but it is easy to fall off, and the real protection time is not long.
When the eggshell is broken and removed, it can be seen that there is a membrane under the eggshell that wraps the contents of the egg, that is, the shell membrane. It is divided into inner layer and outer layer, the inner layer is called protein membrane and the outer layer is called shell intima. The protein membrane and eggshell inner membrane form a sac at the blunt end of the egg, which is called an air chamber. Its diameter is about 1.3 ~ 1.5 cm 24 hours after laying eggs. The longer the egg is left, the more water in it will evaporate and the area of the air chamber will gradually increase. Therefore, the freshness of eggs can usually be judged by observing the size of the air chamber.
Protein is a viscous semi-flowing transparent body. According to its composition, viscosity and function, it can be divided into four layers: frenulum and frenulum layer concentrated protein (or internal concentrated protein), internal diluted protein, concentrated protein (or external concentrated protein) and external diluted protein. Protein accumulates around the yolk in the form of concentric layers, which can protect the blastoderm and provide nutrients for the later stage of embryo development.
The yolk is located in the center of the egg, with obvious outline, round and high convex, and can be changed when shaken. Egg yolk consists of egg yolk spheres of different sizes and shapes. On the surface of egg yolk, there is a light and tiny circular spot, which is called ovule before fertilization and blastoderm after fertilization. When hatching, the embryo begins to develop from the blastoderm into a chicken.
Lace is a band at both ends of egg yolk, which plays a role in fixing the position of egg yolk.