Eggs are divided into?

By construction,

Eggshell

The structure of the egg

The complete eggshell is in the shape of an egg oval, with one end large and one end small, accounting for about 11 to 11.5 percent of the volume of the whole egg. The eggshell can be subdivided into the suprashell membrane, the subshell skin, and the air chambers.

The main component of eggshell is calcium carbonate (calcium carbonate), accounting for about 91% to 95% of the mass of the whole eggshell, and its calcium content is the same as the pearl, oyster, cow bone, small dried fish, is a good source of calcium. In addition, the eggshell also contains about 5% of the magnesium carbonate (magnesium carbonate), and 2% of the calcium phosphate (calcium phosphate) and colloid (colloid).

Shell membrane: that is, on the outside of the eggshell, an opaque, structureless membrane; the role is to prevent the evaporation of water from the egg.

Subshell: the membrane inside the eggshell, **** two layers; air can pass freely through this membrane.

Air chamber: the space between the two layers of the hypodermis; if the gas inside the egg is lost, the air chamber grows.

After the eggshell has been soaked in vinegar or some acidic solution for some time, the shell disappears and it becomes a shell-less egg, with only a thin membrane remaining.

Shell membrane

Shell membrane (shell membrane) is a fibrous membrane wrapped around the egg white, which is a network of organic fibers made of tough keratin.

Shell membrane is divided into two layers: shell membrane is thicker, close to the eggshell, is a layer of opaque, non-structural membrane, the role is to avoid evaporation of the contents of the egg; shell membrane is about 1/3 of the thickness of the former, attached to the shell membrane in the inner layer of the air can freely pass through this membrane.

The inner shell membrane and the outer shell membrane are mostly tightly jointed, only at the blunt end of the egg, the two separated to form the air chamber (air sac).

The air sac appears only after the egg has been laid, as a result of contraction caused by the difference in temperature between the interior and exterior of the body and the formation of a space between the shell membranes; if moisture is lost from the egg, the air sac will continue to increase in size; when the fertilized egg is hatched, it will increase in size with the development of the embryo.

Egg white

Egg white is a semi-fluid gelatinous substance in the sub-shell skin, which makes up about 57-58.5% of the whole egg by volume.

Egg white contains about 12% protein, mainly ovalbumin. Egg white also contains a certain amount of riboflavin, niacin, biotin and calcium, phosphorus, iron and other substances.

Egg white is divided into concentrated egg white, dilute egg white. Concentrated egg white: the part of the egg white near the yolk, the concentration is higher.

Thin egg white: the part of the egg white near the shell, the concentration is thin.

Yolk

Egg yolk

The yolk resides in the center of the egg white and is suspended from the poles by tethers. Yolk volume of about 30% to 32% of the whole egg, the main constituent material for the yolk phosphoprotein, in addition to the fat content of 28.2%, the fat belongs to the phospholipid class I lecithin.

Embryonic disc

A white spot on the surface of the yolk, the unfertilized is called the embryonic disc, the fertilized is called the ovule, the fertilized egg is further developed into the early embryonic disc.

The embryonic disc of a fertilized egg is about 3 millimeters in diameter, and the ovule of an unfertilized egg is even smaller and will develop into the chicken heart.? [2]?

Yolk tether

The yolk is generally layered, consisting of yellow yolk and white yolk arranged in concentric circles formed between each other, with the yolk heart in the middle, connected to the embryonic disk by the neck of the yolk heart and along the long axis of the egg, the yolk is made up of thick proteins at both ends of the yolk to form the yolk tether, which maintains the egg cell in the center of the protein, acts as a cushion to prevent the egg from vibrating, and facilitates the egg's hatching.

Corneal layer

The layer of eggshell re-surfacing, similar to the cuticle of the skin.

Vitelline membrane

Vitelline membrane, a part of the fertilized egg of a bird, a membrane immediately above the surface of the egg. It is a primary egg membrane, which develops from the cell membrane of the fertilized egg and serves a protective function. It is formed within the ovary. It is generally believed that it is composed of secretions of follicular cells, the egg itself may also be involved in the formation of the yolk membrane.

Eggshell

The eggshell consists of the inner yolk membrane, the air chambers, the outer yolk membrane, the true shell, and the guard membrane. The inner eggshell membrane and the outer eggshell membrane are collectively known as the eggshell membrane. These two membranes are in close proximity to each other in other parts, but separate at the blunt end to form the air chamber. The thickness of the inner membrane is only 1/3 of that of the outer membrane, which is translucent, allowing only water and small molecules to pass through, and is composed mainly of keratin and a small amount of carbohydrates. The eggshell membrane protects the embryo by maintaining the osmotic pressure and respiration of the bird during embryonic development. The true shell is mainly composed of organic matter (2%) and calcium salts (98%), but also a small amount of citrate, phosphate, and sodium, potassium, magnesium, their composition and proportion in different birds is different, such as the domestic chicken eggshell organic matter to inorganic matter ratio of 1:50. the protective membrane is fully closed, for the transparent protein film. But gull eggs do not have a membrane. Sheath is divided into two layers, the inner layer of the true shell, containing reddish-brown pigment, blue-green pigment, etc., the formation of patchy texture, the outer layer of the protective film to form the base color of the eggshell. The sheath does not affect the gas exchange of the egg, but prevents the excessive loss of water in the egg and prevents the invasion of microorganisms, so this is the reason why the washed eggs are perishable. The eggshell has stomata, which are oval (chickens) or round (gulls) when viewed under high magnification. The apertures are funnel-like, getting narrower from outside to inside. The distribution of stomata is not uniform, and the density of stomata at the blunt end is often greater than that at the sharp end.