Human Ovum – Detail Explanation with Diagram

Ovum is known as an egg cell which is the largest cell in the human body. It is one of the cells apart from sperm from which a new life is formed. An ovum is produced from the ovaries of women and is then released into the fallopian tubes. Fallopian tubes are a muscular hollow organ which are of average between 10 and 14 cm in length.

Ovum also called ova is fertilized by sperm to produce a zygote that rapidly forms into a new organism in the process of fertilization. If an ova does not get fused within 24 hours of ejaculation then it initiates to degenerate and comes out of the body in the form of blood or other components. This process is generally known as the menstrual cycle. The name ovum has been given to haploid female reproductive gamete.

What is Ovum?

Ovum is also called ova which is a female reproductive gamete. It is the largest cell in the human body. It is an egg which is produced by a woman. Oogenesis is a process by which an ovum develops into its mature form. In viviparous animals (that produce babies from their bodies), the ovum is fertilized inside the body of the females. Karl Ernst Von Baer discovered ovum in 1900, 200 years after the discovery of sperm. He found it in the ovaries and follicles of dogs. Ova is a plural form of ovum. Ovum has a round shape and is non-movable in nature. The size of the ovum is small and is about 0.15 mm in human beings.

It is a female reproductive cell and is also called an egg cell. It is produced in the ovaries which have two pairs. Fertilization is a process in which sperm meets ovum to form a zygote. It is a process by which pregnancy begins that lasts for about 9 months in females. The function of the female reproductive gamete also known as ovum is to convey half of the genetic material or DNA in an embryo and the other half genetic material is transferred from the sperm which together makes up the 46 chromosomes in a newborn baby.

Structure of Ovum

The structure of ovum is described as follows:

• The structure of the ovum is basically spherical and is a non-motile gamete. It has a diameter of about 0.15mm in humans.
• The nucleus is located in the center of the ova which is enclosed by cytoplasm.
• The cytoplasm (yolk) of ova is called ooplasm. It has comparatively less amount of yolk in humans and hence it is alecithal.
• The size of the ovum varies in distinct animals and depends on the amount of yolk.
• The outer layer of the ova is known as the cortex and consists of microvilli.
• The function of microvilli is to help the egg to move substances in and out of the ooplasm.
• The human egg is surrounded by three layers i.e., inner thin vitelline membrane, middle zona pellucida,i.e. and outer corona radiata.
• Zona pellucida covers the vitelline membrane and the space between these two membranes is called perivitelline space.
• Layers of epithelial cells make up the last layer(corona radiata) of membrane as the ovum exit the ovarian follicle.
• Every ovum has a nucleus which is large which contains nucleoplasm and is called germinal vesicle.

Ovum Diagram

The following is a labeled diagram of an ovum:

Function of Ovum

The following are the functions of ovum:

• Ovum is an essential part of the process of fertilization.
• Its major function is to transfer the set of chromosomes contributed by the female gamete.
• The process of fertilization is a significant process of life in which a male and female gametes fuses together to form a zygote which is a diploid cell. The site of fertilization is fallopian tube.
• Fallopian tubes are a muscular hollow organ which are of average between 10 and 14 cm in length.
• Production of ovum takes place from ovaries which relases it into oviducts for further processes.
• The largest and most active cell in early embryo is ovum.
• Oocyte undergoes meiosis and become capable for fertilization by becoming mature ovum.
• Ovum along with the sperm cell determines the child’s characteristics.
• It is also responsible for providing nutrition to the growing embryo.

Female Reproductive System

Female Reproductive System includes internal and external parts or organs. This system provides various functions such as sexual intercourse, reproduction and mentruation. The external parts include labia majora, labia minora, clitories, vaginal opening, hymen. The internal parts includes vagina, cervix, uterus, ovaries and fallopian tubes. Eggs in female body are produced in the ovaries which are then moved to the fallopian tube. Fallopian tubes are a muscular hollow organ which are of average between 10 and 14 cm in length. During intercourse, about thousands of sperms are inseminated into the vagina of female.

The sperms move towards the uterus(located in the pelvis in between the bladder the rectum) and arrives at the opening of the fallopian tube. Only the sperms those are of good quality will reach the opening of fallopian tube. After that egg released from the ovary of female enters into the fallopian tube where it gets fertilized within twenty-four hours of intercourse. Surrounded by thousands of sperms, oocyte get fertilized only by one sperm because there is a process known as cortical reaction that restricts polyspermy. If this mechanism fails to happen then the multiple sperm can fuse the egg.

Also Read:

• Difference Between Sperm and Ovum
• NCERT Notes on Human Reproduction Class 12 Chapter 2
• What is Oogenesis?

FAQs – Ovum

1. Is Ovum and Egg the Same Thing?

The only difference between an ovum and an egg is that ovum is an unfertilized state of cell whereas an egg is the fertilized form of ovum. Ovum consist of only maternal genes but an egg contains both maternal and paternal genes after it gets fully fertilized by sperm as both the reproductive gametes transfer half of their genetic materials.

2. What is Ova in Females?

Ova is a plural form of ovum. It is a female reproductive cell and is also called an egg cell. It is produced in the ovaries which has two pairs and lies to the upper right and left of the uterus. Ovaries have an oval shape.

3. What is the meaning of Ovum?

Ovum is a female sex cell which is responsible for generating a new organisms by fusing with sperm (a male sex cell). It is produced in the ovaries of woman.

4. How big is the Woman’s Egg?

Woman’s egg is regarded as one of the largest cell in the human body as it is the biggest cell than any other cell of human. It’s size is about 0.1 mm in diameter. It is also visible from the naked eye.

5. How is the Ovum Released?

A phase named ovulation in the menstrual cycle where ovary releases an ovum(egg). After it gets release it waits for sperm in the fallopian tube to be fertilized. Basically it happen on the 14th day of the 28 day mentrual cycle.