What Is Sperm and Why Is It Vital in Reproduction?
The male reproductive cell is known as sperm or male gamete, in an organism that undergoes sexual reproduction i.e. in anisogamous form. Sperms are motile in nature with flagellum in the case of animals, which is also called spermatozoa, whereas a few red algae and fungi produce non-motile sperm cells which are commonly known as spermatia. Few flowering plants like ferns and some gymnosperms also produce motile sperm while some produce non-motile sperm inside the pollen.
The process of the formation of sperm is known as spermatogenesis. In the case of amniotes like reptiles and mammals sperm formation takes place in the seminiferous tubules of the testes. Sperm cell formation includes various steps like the formation of spermatogonia and it gets differentiated into spermatocytes. Further, these spermatocytes undergo meiosis division and form spermatids. This whole process of formation of sperm takes three months to complete.
Structure of Sperm
Sperm is differentiated into three parts i.e. head, neck, middle piece and tail. The plasma membrane covers the whole body of sperm.
Structure of Sperm:
A. Head Region: They contain acrosome at the apical end, which contains several important enzymes that help the entry of sperm into the ovum. Further, this head region is followed by a haploid elongated nucleus.
B. Middle Region: This region has multiple mitochondria, and these mitochondria provide energy for the movement of sperm, in order for fertilization to take place.
C. Tail Region: This region has a flagellum that protrudes out of the cell body and is helpful in providing vigorous motility to the sperms. This region of sperm helps in swimming by which they can reach towards the ovum. Approximately 200-300 million sperms are ejaculated at once.
Important Role of Different Regions of Sperm:
Each region of sperm has its specific functions, like:
A. Head region contains acrosomes which contain several important enzymes and these enzymes help to enter the egg during fertilization.
B. Mitochondria present in sperm cells provides energy and this energy is used to navigate in the female genital tract.
C. Tail part of sperm helps in locomotion, by which the fertilization process takes place.
D. Sperm has two types of chromosome either X or Y type and these chromosomes are responsible for determining individual sex.
Place Where Sperm are Created:
Sperms are stored, transported and produced in the male reproductive system. Reproductive organs of male are on both the interior and exterior of the pelvic cavity.
Male reproductive organs include the following parts:
A. The testes:
B. The duct system: The duct system contains epididymis and vas deferens also known as sperm duct.
C. The accessory glands: This gland includes seminal vesicles and prostate gland
D. The penis: Through this transfer of sperm occurs during the copulation process.
Production of sperm occurs in the testicles. At the time of puberty, a man can produce a million sperm every day and the size of sperm varies from 0.002 to 0.003 inches. Tubes that are present in the testicles are known as seminiferous tubules which also includes testosterone. Further male sex hormone produced by the male reproductive system causes semen to turn into sperm. Sperm has a tail, which helps in pushing the sperm into a tube behind the testes called the epididymis. Movement of sperm occurs for five weeks in the epididymis region and in this stage, they complete their development. Sperm moves out of epididymis to vas deferens.
Transfer of Sperm into Female Reproductive Tract
The human male produces semen during mating and ejaculation processes, which is done by the penis. Sperms are microscopic in nature and each drop of semen contains thousands of sperms. When the ejaculation process takes place inside the female vagina or genitals, in that case, the movement of sperm takes place from the cervix to the uterus.
At the time of ejaculation approx 300 million sperms are produced but among this 300 million only 1% are able to make their way into the cervix as the remaining are killed by acidic fluid near the vagina. 1% of sperm are able to find their path towards the oviduct, a place where ovaries release their eggs towards the uterus. Out of this, only a few make their way to the fallopian tube and the rest of them die because of the mucus lining in the uterotubal junction.
After going through so many obstacles, inside the female reproductive system, only one sperm manages to do the fertilization process.
Accessory Gland in Male Reproductive System
The accessory glands in males are seminal vesicles and the prostate gland, and these glands secrete fluids that helps in lubrication of the duct system and also nourishes sperm. The major function of the urethra is to carry sperm in the form of semen to the outside of the body with the help of the penis and it is also considered as a part of the urinary system as it is also the channel through which the urination process takes place.
FAQs on Sperm: Structure, Function, and Biological Importance
1. What exactly is a sperm cell?
A sperm cell is the male reproductive cell, also known as a male gamete. It is a microscopic cell whose main purpose is to fuse with the female egg cell (ovum) during fertilisation. Each sperm carries half of the male's genetic information (DNA), which combines with the egg's genetic information to create a new organism.
2. How and where are sperm produced in the male body?
Sperm are produced in the testes through a process called spermatogenesis. This process takes place inside a network of tiny tubes known as the seminiferous tubules. It begins at puberty and continues throughout a male's life, with millions of sperm being produced every day.
3. What are the key differences between a sperm and an ovum?
The sperm and the ovum (egg cell) are very different, as they have distinct roles in reproduction. Key differences include:
- Size: The sperm is the smallest cell in the male body, while the ovum is the largest cell in the female body.
- Motility: Sperm are highly motile, meaning they can move on their own using their tail. The ovum is non-motile.
- Production: Millions of sperm are produced daily, whereas females are born with a finite number of eggs, and typically only one is released per month.
- Structure: A sperm has a distinct head, middle piece, and tail for movement. An ovum is a large, round cell rich in cytoplasm to nourish the early embryo.
4. What are the main parts of a sperm cell and their functions?
A mature sperm cell has three main parts, each with a specific function for reaching and fertilising the egg:
- The Head: Contains the nucleus, which holds the male's genetic material (chromosomes). The tip of the head, called the acrosome, contains enzymes that help the sperm penetrate the outer layer of the egg.
- The Middle Piece: Is packed with mitochondria. These are the "powerhouses" of the cell, providing the energy needed for the tail to move.
- The Tail (Flagellum): This long, whip-like structure propels the sperm forward, allowing it to swim through the female reproductive tract towards the egg.
5. What is the main purpose of a sperm cell in reproduction?
The primary purpose of a sperm cell is to carry the male's genetic information to the female's egg cell and achieve fertilisation. Its structure is highly specialised for this journey—it is designed to travel long distances, penetrate the egg, and successfully combine its DNA with the egg's DNA to initiate the development of an embryo.
6. What factors can affect sperm health and count?
Several factors related to health and lifestyle can impact the quality and quantity of sperm. According to biology studies, key factors include:
- High temperatures: The testes are located outside the body to stay cool, as excessive heat can damage sperm production.
- Diet and Nutrition: A balanced diet rich in antioxidants, vitamins, and minerals supports healthy sperm development.
- Lifestyle choices: Smoking, excessive alcohol consumption, and drug use can negatively affect sperm count and motility.
- Stress: High levels of chronic stress can interfere with the hormones needed for spermatogenesis.
7. Why do sperm cells have a tail but egg cells do not?
The difference in structure is directly related to their function. A sperm cell must travel a long distance from the point of ejaculation to the fallopian tube to find the egg. The tail (flagellum) provides the necessary motility for this journey. The egg cell, or ovum, on the other hand, does not need to travel. It is a passive target, waiting in the fallopian tube to be fertilised. Instead of a tail, it has a large store of cytoplasm to provide nutrients for the embryo in the first few days after fertilisation.
