Pregnancy in the female body occurs as a result of the fusion of two sex cells. One of them is called a sperm cell, and the other is called an egg. What is the size of the sperm? What are the functions of the sex cell? How is a sperm cell different from an egg cell? All these questions are yet to be answered.
Male reproductive system
The function of reproduction in the body of a representative of the strong half of humanity is performed by some glands and organs:
- testicles with appendages;
- vas deferens;
- prostate;
- seminal vesicles;
- bulbourethral glands;
- scrotum;
- penis.
All of the above collectively referred to as the male reproductive system. It produces spermatozoa. This term refers to male germ cells capable of fertilization. During unprotected sex, spermatozoa leave the male reproductive system and enter the female body.
Functions of a specialized cell
Sperm is a structure that contains the genetic information of a man. The functions of a specialized cell of the male body are several:
- passing through a woman's genital tract (the size and structure of a human sperm cell allows it to overcome various obstacles);
- penetrating the female sex cell called the ovum;
- introducing genetic material into it.
It is worth noting that during intimacy, sperm enters the woman's body. It consists of seminal fluid and spermatozoa suspended in it. Male germ cells in the sperm contains a huge amount. But a mature egg in the female body is just the only one. Only one male sex cell manages to fulfill all its functions. A huge role in this is played by the size and shape of the sperm.
Sperm structure: head and neck
The male germ cell is characterized by a specific shape that provides the ability to move, fertilize the egg. The sperm cell is an oval structure with a long flagellum. What is the structure of this cell? So, the sperm is represented by three components:
- head;
- neck;
- tail.
The head is the oval part of the sperm. At its top is the acrosome. This is the name of a vial with special substances necessary for penetration through the protective shell of the egg. The head also contains the nucleus. It stores half of the male genetic information (DNA). Another component of the head is the centrosome. It contributes to the movement of the tail.
The second part of the sperm is the cervix. She isis a fibrous region connecting the head and tail. This structure is very flexible. This feature ensures the movement of the sperm. Due to its flexibility, the head oscillates from side to side.
Sperm tail structure
Before describing the size of the spermatozoon, it is worth considering its third part - this is the flagellum. It is also called the tail. It includes several sections:
- Intermediate. This is the thickest part of the sperm tail. It has a spiral mitochondrial layer that produces energy for the movement of the male germ cell.
- Chief. This section of the spermatozoon consists of microtubules. They are covered with an outer layer of dense fibers and a protective sheath.
- Terminal. On this part of the spermatozoon, the protective sheath and dense fibers become thinner. The coating is a thin cell membrane.
Familiarizing with the structure of the last part of the sperm, we can conclude that the tail gradually narrows from its base to the end. This feature provides whip-like movements of the male germ cell when moving through the female reproductive tract in search of an egg.
Sperm size
The male sex cell is very small. Human sperm size is as follows:
- total cell length - about 55 microns;
- head height - 2.5 microns, width - 3.5 microns, length - 5.0 microns;
- sperm neck - about 4.5 microns in length;
- tail length - 45 microns.
Male reproductive cells cannot be seen with the naked eye. The size of a spermatozoon can be seen under a microscope. This is what Leeuwenhoek once did. In 1677 he described spermatozoa. The scientist, having made the discovery, suggested that these cells are involved in fertilization. However, this information was not taken seriously in society. For about 100 years, mankind considered spermatozoa to be parasitic microorganisms.
Formation of male reproductive cells
The question of how big spermatozoa are has been answered. Now it is worth considering how these cells are formed. Spermatozoa originate and mature in special glands called testicles. These structures are located in the scrotum. They contain a huge number of seminiferous tubules lined with special cells (spermatogonia). How are male sex cells formed here? This process begins at puberty:
- spermatogonia divide;
- as a result, new cells appear;
- Sperms mature thanks to Sertoli cells secreting various nutrients.
The process of formation of male germ cells is called spermatogenesis. It's quite complex. The process does not end with the formation of primary spermatocytes, because the cells that have appeared have a complete set of chromosomes. These cells then undergo meiosis. As a result, spermatids with a half set of chromosomes appear. Cells gradually grow and develop. ATthe result is mature spermatozoa.
Movement of male reproductive cells
Having considered the function and size of the sperm, you need to familiarize yourself with how the sex cell moves. Spermatozoa in the male body are inactive. They move passively through the genital tract. The movements of the tails are quite insignificant. Spermatozoa acquire activity after entering the female body. Their speed can be more than 30 cm per hour.
After ejaculation, more than 300 million sperm enter the woman's body. Most of them die in the vagina due to the unfavorable environment. Some male germ cells manage to reach the cervical canal. However, not all spermatozoa manage to pass this section of the path. Cervical mucus becomes an obstacle for them.
Spermatozoa that pass through the cervical canal enter the uterus. The environment in this internal organ is favorable for male germ cells. From the uterus, they travel to the fallopian tubes, where fertilization takes place. Studies have shown that only a few thousand spermatozoa pass this way.
Sperm Lifespan
Cell formation lasts approximately 74 days. Maturation and their passage through the epididymis and vas deferens takes about 26 days. The conclusion suggests itself that spermatozoa can stay in the male body for a long time. A completely different situation is observed after ejaculation. In sperm, germ cells remain active for no more than a day.(The duration of this period depends on external factors such as ambient temperature, amount of light, humidity).
In the female body, their life expectancy can be different. If the size of the sperm affects the speed of movement, then the duration of existence does not depend on this. For example, in the vagina, male germ cells die in 2 hours. In the uterus and fallopian tubes, the environment is more favorable for spermatozoa. Here they can stay active for up to 5 days in search of or waiting for an egg.
Comparison of sperm and eggs
In the body of a man, new germ cells are periodically formed and mature. With each sexual intercourse, semen is released, containing a huge amount of spermatozoa. But in a woman's body, only one germ cell matures in one menstrual cycle (approximately 28-30 days).
Now it's time to compare the size of the egg and sperm. The male reproductive cell, as mentioned above, is a tiny structure. The egg is completely different. Its dimensions can be from 0.15 to 0.25 mm. It is also worth noting that the egg is immobile. In addition, she has a rather short lifespan. After leaving the ovary and entering the fallopian tube, it can exist for about 24 hours. If fertilization does not occur, then the egg dies.
In conclusion, it is worth noting that the size of the spermvery small. Despite this, it has an important function, which is the fertilization of the egg. However, not all spermatozoa are capable of doing this. Once in the female body, they undergo natural selection. Weak cells that have an irregular structure die very quickly before reaching the uterus. The rest simply do not have time to reach the goal. Only the fastest and most active spermatozoon, having bypassed all obstacles, penetrates the found egg and adds its genetic information to it.
