Maturation

Maturation of Egg refers to the entire process of an egg’s development from its conception (gametogenesis or oogenesis) to its maturity and finally fertilisation. Oogenesis is the type of gametogenesis in which ova, also known as female gametes, are produced, and the female gamete that is produced is referred to as an ovum. Oogenesis is the process by which ova are produced, and the female gamete that is produced is referred to as an ovum. In general, female gametes are referred to as eggs; however, the term egg can refer to various stages of development, and the significance of an egg varies depending on the type of organism being discussed.

As an illustration, When birds lay eggs, the entire development (or maturation) of an egg, from conception to hatching, and the transformation of the egg into a chick takes place entirely within the eggs themselves. On the other hand, in placental mammals, once the egg has fully developed and been fertilised, it begins to divide, and it is no longer referred to as an egg. It is important to remember that every ovum must be haploid, meaning that it must contain a single copy of every chromosome.

Oogenesis

Oogenesis is the process by which the ovum develops. In the world of gametogenesis, spermatogenesis and oogenesis are two different types of gametogenesis. The process of gametogenesis in the male is known as spermatogenesis, and the process of gametogenesis in the female is known as oogenesis, which results in the formation of ovaries in females. In several ways, oogenesis and spermatogenesis are diametrically opposed to one another.

What exactly is Oogenesis?

It is the process of forming female gametes that is referred to as oogenesis. During pregnancy, this process begins inside the foetus and continues until birth. The stages of oogenesis leading up to the production of primary oocytes take place before the birth of the child. Primary oocytes are incapable of further division. Either they develop into secondary oocytes or they degenerate.

The process of oogenesis takes place in the outermost layers of the ovaries. Oogenesis begins with the formation of a germ cell known as the oogonium, which then undergoes mitosis in order to multiply. It is necessary to distinguish between the three stages of oogenesis:

Prenatal

Antral

Pre-ovulatory

Process of Oogenesis

The process of oogenesis is completed in the three stages that are listed below:

Pre-natal Stage

The primary oocyte continues to develop while it is halted in meiosis I. The follicular cells proliferate and form a stratified cuboidal epithelium as a result of this proliferation. Granulosa cells are the name given to these types of cells. During the development of the zona pellucida, glycoproteins are secreted by these cells around the primary oocyte.

Antral Stage

The fluid-filled space between granulosa cells joins together to form the antrum, which is a central fluid-filled space in the centre of the cell. Secondary follicles are what these are referred to as. These secondary follicles develop in every month cycle under the influence of follicle-stimulating hormone and luteinizing hormone, and they are responsible for the production of eggs.

Pre-Ovulatory Stage

This stage is induced by the LH surge, and it is during this stage that meiosis-I is completed. Within the follicle, the formation of two haploid cells of unequal size occurs. One of the daughter cells that receives less cytoplasm develops into a polar body as a result of this. This cell does not take part in the development of the ovum. The secondary oocyte is the name given to the other daughter cell. Meiosis II is carried out by the two daughter cells. The polar body divides into two polar bodies, while the secondary oocyte remains in the metaphase stage of meiosis-II, preventing further division.

Ovulation

The ovaries are responsible for the development of oocytes. Every oocyte is surrounded by follicle cells, which join together to form a follicle.

Beginning with the onset of the menstrual cycle, primary oocytes begin to grow in size, and the number of follicle cells increases, causing the follicle to grow in size as well.

Normally, some of the nurturing oocytes degenerate, resulting in only one follicle being able to mature. It is possible to have fraternal twins who are genetically distinct in this environment.

When a follicle reaches maturity, the primary oocyte completes its first meiotic division and transitions to the status of secondary oocyte. Immediately following, the follicle ruptures, and the secondary oocyte is released into the fallopian tube, even though the second meiotic division has not yet taken place. Ovulation is the term used to describe the release of a secondary oocyte from the ovaries.

Fertilisation

Fertilisation results in the completion of Meiosis-II. This results in the emission of a third polar body. If fertilisation does not take place, the oocyte degenerates 24 hours after ovulation while remaining in the meiotic phase II cell division (meiosis II).

The most significant difference between oogenesis and spermatogenesis is that oogenesis occurs in the foetus prior to birth, whereas spermatogenesis occurs after birth.

Conclusion

Oogenesis is the process by which an ovum (egg cell) differentiates into a cell that is capable of further development when fertilised. It develops from the primary oocyte through the process of maturation. The process of oogenesis begins during the embryonic stage.