Discover ALL the parts of an egg

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The ovum is the female sex cell. Although they have the same function, the egg and the sperm have different appearance and different parts that allow all the functions that are performed here to be carried out. It is important to know that the ovum is the cell that is shed from the ovary during menstruation and, therefore Therefore, it is one of the essential elements, together with the spermatozoa, for the reproduction of the lifetime. In this lesson from a TEACHER we are going to tell you what are the parts of the ovum.

Index

1. What is the ovum
2. The nucleus, one of the main parts of the ovum
3. The yolk of the ovum
4. The cortical granules of the ovum
5. The cytoplasmic membrane or ovolemma
6. The zona pellucida
7. The corona radiata of the ovum or corona radiata
8. The parts of an ovum, can they change?

The ovum is the female reproductive cell and is in charge of carrying the maternal genetic information to the new individual and nourish to the embryo during the first days of life. Unlike the sperm, the ovum is a large, spherical and almost immobile cell in which we can distinguish mainly: the nucleus, the yolk and various membranes and layers of cells that serve to protect them. If you want to know more about what are the parts of an ovum and their functions, read on!

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The core it is one of the main parts of an ovum since contains the genetic information that will be inherited from the mother to the future embryo. Unlike the rest of the cells of the body, and like it is sperm, the ovum has 23 chromosomes.

Gametes, which have half the chromosomes of cells in the rest of the body, are said to be haploid. This allows the egg and sperm to unite (fertilization) a cell forms (zygote) with the right number of chromosomes: 46.

Sometimes this part of the egg may also be called the pronucleus or ovular pronucleus.

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The yolk it is another part of the ovum. Specifically, it is the reserve substance that allows the embryo to nourish itself during the first days of life. These substances are proteins, carbohydrates and lipids.

In the case of humans, the amount of yolk necessary is not going to be much since we only need the embryo to feed on it until the placenta is formed, but in other animals the amount of yolk that is needed is very large because the embryo will feed on it until born.

This is, for example, what happens in chickens, in which all the white of the egg is the yolk that sustains the embryo until it hatches from the egg.

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The cortical granules They are small spherical organelles that contain substances such as sugars and hydrolytic enzymes. These substances are very important since they are released when the union with the sperm occurs and allows membranes to break that separate the pronuclei from the ovule and the sperm.

Sometimes these cortical granules are displaced by the yolk and nucleus to the periphery of the ovum and are seen as a band. This band is called cortex.

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The cytoplasmic membrane is the first envelope surrounding the nucleus, yolk, and cortical granules. This membrane is very thin and allows the exchange of different substances, called ions. Furthermore, at the time of fertilization, this cytoplasmic membrane has to unite and merge with that of the sperm so that the DNA of both can join.

The cytoplasmic membrane of the ovule can also be called the ovolemma or oolema, a name that was given shortly after discovering its existence.

The pellucid zone it is another part of the ovum. It is a layer of gelatinous substance that forms around the cytoplasmic membrane to protect first the ovum and then the pre-embryo. It is made up of glycoproteins, molecules that play an important role in the recognition and attachment of sperm during fertilization. Furthermore, this layer of glycoproteins hardens after fertilization, which makes it more difficult for more than one sperm to join the same egg (polyspermia). They also have immune functions.

Within the parts of an ovum, this It's very important and alterations due to the woman's age can cause abnormal embryos to be produced. In mammals this layer is called the zona pellucida, but in other living beings it is called the vitelline membrane and It is composed of other types of substances, but its function is similar to the one we have explained previously.

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The corona radiata It is a layer formed by a gelatinous substance rich in hyaluronic acid and cells called follicular or granulosa cells. This layer surrounds the zona pellucida and it has three functions: on the one hand, it protects the ovum from possible damage during its journey from the ovaries to the uterus, on the other it produces sex hormones and, finally, it intervenes in the formation of the placenta.

These cells are said accompany the embryo and disappear when it joins and invades the mother's uterus (uterine implantation). This process is called hatching and it is very important for the embryo to develop.

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The ovum is a cell formed in the ovary that undergoes a series of changes from the moment it is formed until it is ready for fertilization by the sperm. This process is called oogenesis or oogenesis And yes, indeed, the parts of the ovum change during their maturation.

Oogenesis begins with the formation of the embryo and is paused until the female is physically ready to be fertile. When this happens, oogenesis continues and women mature our eggs, one by one, throughout our fertile stage through menstrual cycles.

In addition to during its maturation, the parts of an ovum they will change when fertilization occurs. Do you want to know more about the phases of fertilization and how both the ovum and the sperm change? Check out our lesson on phases of fertilization!

If you want to read more articles similar to Parts of an egg, we recommend that you enter our category of biology.