Chicken eggs are single cells

Chicken eggs are essential foods for humans. But the egg is not only important for human nutrition; Even the unborn chick receives all the proteins, fats, carbohydrates, minerals and vitamins from the egg yolk, egg white and shell that are necessary to nourish it during incubation (21 days).

Since the development of the embryo begins within the hen’s reproductive organs, it is important to understand the structure of an egg and the hen’s reproductive system. The hen’s reproductive organs are the ovary and fallopian tubes (Figure 2). The location of these organs in the animal is shown schematically in Figure 1.

Most females in the animal kingdom have two functioning ovaries, but the hen only has one. Right ovary development stops when the (female) chick is hatched while the left ovary continues to develop. The left ovary contains up to 4,000 tiny eggs, the largest of which develop into egg yolks as the hen grows.
Each yolk is surrounded by a thin follicle (sac) made of membranes. Blood vessels in the follicle carry nutrients to the developing yolk. When an egg yolk matures, the follicle breaks through along a line that is relatively free of blood vessels. The yolk is thus released. The yolk remains intact as it is protected by a membrane.

Once released from the follicle, the yolk enters the body cavity. There it is picked up by the funnel (see Figure 2) and begins its way into and through the fallopian tube. The fallopian tube is about 60 cm long; it is equipped with glands that secrete substances that are still needed for the finished egg. Initially, only the yolk is in the fallopian tube; the egg white, the membranes of the shell and the shell are still missing. The "material" for these components comes from glands (see Figure 2). Around 24 hours are needed to rearrange the yolk with these materials and thus to complete the egg.

The finished egg is basically a highly complex reproductive cell (Figure 3), which is responsible for a new life. The germ spot (often called the germinal disc) from which the new chick develops is on the yolk. The egg white surrounds the germ cell and protects it. It consists of several layers.

The egg white is an elastic, shock-absorbing, semi-rigid material with a high water content. The yolk and white of the egg serve as food for the growing embryo during incubation. On opposite sides of the yolk are two twisted cord-like cords called hail cords. They keep the egg yolk in suspension in the egg white so that it doesn't hit the shell. The germ spot is always on the upper side of the yolk and therefore close to the hen's body heat. This is important during the incubation process. The yolks and whites therefore work together to protect and support the life of the growing embryo.

Around the egg white and the egg yolk there are two shell membranes and the shell itself. These additionally protect the egg yolk and the egg white, the shell also ensures the exchange of gases.

Fig. 1: Position of the ovary in a hen

Fig. 2: Hen's reproductive system

Fig.3: Structure of a chicken egg

The following table summarizes the function of the egg components:
Egg yolk, Egg yolk:Nutrition, protection of the embryo
Protein, Egg whiteNutrition, protection of the embryo. The egg white turns white when cooked ("egg white")!
Membranes, "Egg skin"ensures breathing, i.e. the gas exchange between oxygen and carbon dioxide
Bowl, Lime bowlProtection of the embryo from mechanical damage
HailstonesThey hold the yolks in a floating position
Germinal disc, Germ stainK. is a small white spot from which the chick develops through cell division and growth.
Air chamberMake sure the chick has enough room to hatch.