Men and women are arranged by nature in different ways, and the differences between them also exist at the cellular level. Male and female reproductive cells have a number of interesting features in their structure. This article will tell you about how sperm and eggs are arranged, as well as how they differ.
Sperm structure
For the first time a scientific description of the anatomy of the male reproductive cell was made by the Dutch researcher Anthony van Leeuwenhoek. He did this in 1677, while not only describing the main elements of the male reproductive cell, but also making sketches. Until that time, scientists had no idea how fertilization occurs, but after Levenguk's discovery, it became obvious that male germ cells - sperm cells - are involved in the process of conception.
Interestingly, for quite a long period of time, sperm were called "seminal animals." The familiar name of sperm was received only in the 19th century.
Every cell in the human body has a number of important characteristics and must perform specific functions. The main role of the sperm is to reach the woman's fallopian tube, fertilize and provide its genetic material.
Each cell has its own set of chromosomes, and it is in them that a special genetic code is located. Each chromosome carries information about what signs a person will have in the future. So, genes that are in a certain sequence on the chromosomes determine a particular hair color or eye shape.
The size of the male reproductive cell is slightly smaller than that of the female. Modern scientists have even established the length of the sperm - it is approximately 55 microns.
In appearance, the sperm is very similar to a tadpole. It has a head, body (middle part) and a tail. Each of these divisions has its own length. The sizes of the main parts of the sperm are shown in the table below.
In the process of sperm development, a number of very important transformations take place - it must fully mature and become suitable for conception. During maturation, the sperm is significantly reduced in size. His nucleus thickens and the amount of cytoplasm decreases, while all the necessary intracellular organelles remain.
The middle part of the sperm is separated from its head by a certain constriction called the neck. Behind the middle part is a movable tail, due to which sperm are characterized by the ability to move. Inactive and inactive male germ cells, the possibility of conception is significantly reduced. In order for the sperm to enter the fallopian tube, where it can meet with the egg, it needs to be sufficiently mobile. The tail helps him in this - with the help of it the sperm makes movements around its own axis.
Scientists also calculated the average speed of movement of motile sperm. So, it is approximately from 0.1 mm per second to 30 cm per hour. It is believed that after intercourse, active sperm are able to reach the fallopian tube in almost 1-2 hours.
In order to be active, sperm need prostatic juice. It is produced by the secretory genital organ of a man - the prostate.
During ejaculation, sperm cells activated by prostatic juice can carry out their movement for further fertilization.
See the next video for more details.
Oocyte structure
The number of female follicles is determined even in the period of intrauterine development. In a little girl who is still developing in the womb, eggs begin to form. By the time of birth, their number is about 1-1.5 million.
Female and male sex cells have certain similarities. So, eggs, like spermatozoa, are necessary for fertilization. Inside the female reproductive cell there is a nucleus - in it, like in the head of a sperm, there is also a certain set of chromosomes that encodes important genetic information.
Outside, the egg is surrounded by an outer shell. It is made up of special proteins. The special structure of the outer shell of the egg contributes to the fact that only one spermatozoon can penetrate into it at the time of fertilization.
The outer shell of the egg is also called the radiant crown, as it is covered from the outside with a large number of microscopic villi. They are necessary in order to provide protection for the small cell.
An important property of the female reproductive cell is its maturation. In each menstrual cycle, one egg matures in a woman's body. In the process of maturation, the female reproductive cell goes through several phases successively replacing each other.
Female eggs develop within a few days of the menstrual cycle. During ovulation, a mature egg leaves the follicle and enters the fallopian tube. If a meeting with sperm does not occur, she dies. In this case, pregnancy does not occur.
The eggs mature in the female body only during the reproductive period - this is the time when a woman can become a mother naturally. The reproductive time begins with the arrival of the first menstruation and ends with the final onset of menopause.
Throughout life, the number of eggs given by nature since birth changes. This is influenced by a lot of environmental factors. Among the most common reasons for a decrease in the number of eggs in the female body are stressful influences, concomitant gynecological diseases, as well as bad habits.
In the case of persistent violations of the process of maturation of eggs in the ovaries, a woman may face the problem of infertility.
You will learn more about eggs in the following video.
Differences between sex cells
Male and female cells have a number of differences. Comparative characteristics include several criteria.
First of all, male and female germ cells differ in size. The egg cell is somewhat larger than the sperm cell because it has a different structure. So, there is more cytoplasm inside it. The size of the female reproductive cell is approximately 130 microns, that is, approximately twice the size of the male.
Also, sex cells in men and women differ in the set of chromosomes. The main genetic information is located in the nucleus - the main organ of the small reproductive cell. This is where the chromosomes are located.
Scientists distinguish only two types of sex chromosomes - X and Y. The presence of a Y chromosome in the genotype predetermines the birth of a boy, but paired X chromosomes are "responsible" for the future birth of a little girl.
The Y chromosome is found only in the sperm. Thus, the birth of an heir is possible only if, at the time of conception, fertilization was carried out under the influence of a sperm that contains a Y chromosome. The baby can only "get" her from the dad, since she simply does not exist in the female body.
Comparisons between eggs and sperm can also be made in terms of their ability to survive. By this term, specialists mean the ability of a cell to survive in external conditions without losing its basic properties and viability. It is believed that sperm cells are more viable than eggs. So, on average, they can persist in the female genital tract after intercourse for 3-4 days, while an unfertilized egg dies relatively quickly - 12-24 hours after its release from the follicle.
