Sperm Cells – Definition, Function, Structure, Adaptations, Microscopy

Sperm Cells - Definition, Function, Structure, Adaptations, Microscopy

Sperm cells are needed when it comes to fertilization, but what exactly are they? How do they work? And what’s their structure like? 

This article will be answering all these questions, and will give you a complete guide to all things sperm cells! 

What Are Sperm Cells?

Sperm cells are reproductive cells, also known as gametes, that are produced by male animals and human beings. 

They are produced in the testicular organ and contain 23 chromosomes – structures made of DNA, and these are the result of meiosis, which is when a cell divides itself in order to produce four cells.

These cells then contain half of the genetic information from the original cell. 

How Are They Produced?

As mentioned above, sperm cells are produced in the testicular organ of male animals and humans. 

The testicles house some very small tubes, known as the seminiferous tubules, and here is where the sex cells that will eventually be turned into sperm by testosterone, live. 

The sex cells will move into the epididymis, which is a tube behind the testes, and will travel around this tube until they fully develop. 

Once their development is completed, they will move to the vas deferens before being moved again to the urethra.

The urethra is a tube that transfers semen and urine away from the body. The urethra is where the sperm cells will prepare for ejaculation. 

When the sperm cells are stimulated from sexual activity, they will then mix together with seminal fluid to produce semen. 

Once the person has been stimulated enough, ejaculation will take place. During this, around 500 million sperm will be pushed from the penis through the urethra tube. 

The process of sperm cells being created and growing until they mature is called spermatogenesis, and the full cycle takes around 74 days. 

As mentioned above, in one ejaculation, up to 500 million sperm can be present, and those individuals with less than 15 million sperm in a millimeter of semen are generally considered to have a low sperm count. 

Function

The function of a sperm cell is to be released during ejaculation (during sexual intercourse) and come into contact with an egg cell, known as an ovum, produced by a female body. 

Once the two come into contact, the sperm will fertilize the egg, creating a cell combination called a zygote. This cell will then divide for a few days after the egg has been fertilized. 

This cell will then develop into a blastocyst and implant in the uterus after around 5 days. This is what will then become a fetus. 

Structure Of A Sperm

The general structure of a sperm cell involves three parts. The head, body, and tail. While this is their general structure, not all of these cells look the same, and they may vary in shape and size. 

In general, their head is usually oval in shape and has a smooth surface.

Their body, which is their middle section, is normally slim and the same length as their head. Their tail is usually the thinnest part of the sperm cell. 

The Head Of A Sperm

Mature sperm cells have an oval-shaped head, resembling an egg. They are usually 2.5 t0 3.5 um (micrometers) wide, and 4 to 5.5 um long. 

This part of the sperm cell is the most important, as it contains the nucleus, which holds the 23 chromosomes. This is what holds the DNA of the sperm cell. 

Once the sperm and egg come into contact, they combine and make 46 chromosomes together.

It is these chromosomes that will establish the different characteristics of the fetus, such as eye color, hair, color, and color of skin.  

The sperm cells will also carry the X or Y chromosomes, and it is these that determine the gender of the fetus. 

Aside from containing the nucleus, the head of the sperm has a cap called the acrosome.

This structure has important enzymes that aid the sperm when it comes to entering an egg. 

Midpiece Of A Sperm

The midpiece of a sperm cell lies between the head and the tail. It makes up 10 percent of the entire length and contains mitochondria. 

Mitochondria are organelles located in cells, and they create chemical energy that these cells need in order to survive.

They are known as the ‘powerhouse’ of a cell, so while the head of a sperm contains the important nucleus and chromosomes, this midpiece is what keeps the sperm cell alive.

The Tail Of A Sperm

As one would assume, the tail is what gives the sperm cell movement. It is thin and long and makes up around 80% of the sperm cell’s structure. 

There are a few parts that make up the tail of the sperm cell. The connecting piece, which is what connects the tail of the sperm to the head.

The principal piece is what generates the waveform and mobility in order for the sperm to move. Finally, the end piece also helps with mobility. 

The tail movement of the sperm cell will not necessarily activate until the sperm has been pushed to relative proximity to the egg.

Holding off until it is within a short distance of the egg, increases the chances of the sperm being able to reach and fertilize the egg before tiring out. 

Motility

Motility

Motility refers to sperm being able to move, or swim, accordingly. Sperm must be able to move in order for sexual intercourse to lead to conception. 

A male will ejaculate at the end of the vaginal canal, and sperm will then swim up through the rest of this canal and make their way to the cervix. 

However, this can also happen without ejaculation.

While sexual intercourse is taking place, or when a male is aroused, a semen-like fluid can escape through the urethra, known as pre-ejaculate. 

Sometimes, this sperm-like fluid can contain sperm cells that can swim up the vaginal canal and reach an egg, which is why the ‘pull-out’ method isn’t a useful form of contraception. 

While the egg doesn’t move, it sort of floats, the sperm are programmed to move themselves to reach their desired location, which is the egg.

Sperm have the ability to swim all the way up the vaginal canal to the fallopian tube, where they will meet the egg that has been released during ovulation. 

It has been noted that sperm can take between 2 and 10 minutes to reach the fallopian tubes, where the desired egg lies, after ejaculation. 

There are two types of motility that have been studied and noted in sperm cells.

Activated Motility 

This type of motility is usually observed in the early stages, such as when sperm has only just been ejaculated.

It involves the sperm beating gently from side to side as it moves along a straight path. 

Hyperactivated Motility 

This type of motility normally takes place once the sperm is inside the reproductive area of the female. 

This kind of motility is more erratic than the one mentioned above and resembles a waveform that is symmetrical in movement.

This kind of motility uses more energy and will prevent it from becoming stuck or trapped within the female reproductive system. 

It also ensures the sperm are able to propel themselves through the reproductive system and gives them more chance of penetrating an egg. 

In order for sperm to be able to move on their own, they have to be healthy and of good quality.

As a person ages, the motility and quality of their sperm will decrease, but there are other factors that can diminish the quality of sperm. 

These include the use of illegal drugs and excessive alcohol consumption, taking steroids, smoking cigarettes, and being relatively inactive as an individual. 

In some cases, making some lifestyle changes can improve fertility. 

Can You Improve Sperm Count And Quality?

Can You Improve Sperm Count And Quality?

Doctors usually consider a low sperm count to be less than 15 million per ml of semen.

Sperm cells must also be of good quality in order for them to be able to move and swim in order to reach the egg. 

Testosterone levels are though to be one of the leading causes in low sperm count and low sperm quality, but there are also some medical conditions that can cause this, such as infections, cancers, and genetic disorders. 

Despite this, as mentioned above, there are some natural ways to improve the hormones that control the production of sperm, that could then lead to healthier sperm production. 

Studies have shown that exercise and weight loss can improve the sperm count of those who are overweight or obese. 

They have also shown that those who are moderate or heavy smokers had a reduced sperm count than those who were not. 

While further research is needed, some studies have shown links between excessive alcohol and drug use to fewer sperm production. 

Looking at the research, it is safe to say that taking part in regular exercise, reducing alcohol and drug use and quitting smoking could improve sperm count and quality. 

Aside from incorporating a healthy lifestyle, there are a few natural remedies you can try. 

Fenugreek has often been used to improve sperm health, and studies have shown that this natural remedy can sometimes improve sperm count and quality.

Fenugreek supplements are often available in health stores or online. 

While more research needs to be done on the topic, there are links between good levels of vitamin D and calcium and good sperm health.

Therefore, taking a vitamin D supplement could be a good way forward. 

Ashwagandha has long been known for its ability to aid in the relief of symptoms of menopause in women, but studies have shown it can increase sperm count.

These supplements are also available online. 

Antioxidants are useful at counteracting free radicals which damage cells. There are many foods and vitamins that contain antioxidants, and these have been shown to improve sperm health.

Some of these include vitamin C, lutein, and beta-carotene. 

Those having sperm issues should also limit any foods that are rich in estrogen, as this can interfere with testosterone production, which is needed for healthy sperm.

Foods that are high in estrogen include soybeans, chickpeas, flaxseeds, and cashews among many others.

While trying these natural remedies may not solve your fertility issues, they may improve the health of your sperm, which is always a step in the right direction.  

Sperm Count

As mentioned already, the testicles produce millions of sperm every day, but this can depend on the individual. 

While studies show that testicle size does not determine how much sperm someone produces, it can sometimes depend on ethnicity. 

A study showed that the daily sperm production levels for white males was 193 to 318 million sperm every day. 

Hispanic males produce 231 to 398 million each day, and Chinese males produced 70 to 173 million sperm each day. 

If a couple are struggling to conceive for a year, it is recommended that they visit a doctor in order for them to analyze their semen. 

Sometimes, a person may have a very low, or no sperm in their ejaculate. However, this may not always mean that the testicles aren’t producing sperm.

Sometimes, there may be a blockage that is preventing the sperm cells from coming through.

Therefore, it is always best to visit a doctor if there is trouble conceiving for an extended period of time. 

How Long Do Sperm Live?

Knowing how long sperm can survive is an important factor when it comes to conceiving.

If sperm are released on a dry surface, then they will die the minute the sperm dries. 

They are, however, able to live longer if they are released in water, as they thrive in wet, warm places. 

It is important to note that sperm can live inside a female body for around 5 days.

Therefore, if intercourse without protection takes place and a male has ejaculated inside the female’s body, if this happens before ovulation, there is a chance that the female can get pregnant when she starts to ovulate. 

How Many Sperm Do You Need To Conceive?

How Many Sperm Do You Need To Conceive?

As mentioned earlier in this article, each ejaculation leads to millions and millions of sperm being released. However, it only takes one sperm to fertilize an egg. 

The journey from the vaginal canal to the fallopian tubes is strenuous, and only a few sperm will survive this tough journey.

Therefore, millions of sperm are released in order for the few strong ones to make their way to the desired location. 

Some experts believe that this is nature’s way of ensuring that the healthiest sperm is the one to fertilize the egg, leading to a healthy, strong baby. 

Adaptations Of Sperm Cells

In order for sperm cells to function accordingly, there are certain adaptations that allow this. For example, sperm cells have a streamlined body.

This allows it to swim freely and smoothly, in order to reach the egg. Aside from this, the head of each sperm cell has a tapering apex.

This reduces drag, giving the sperm an even smoother journey in order to reach the egg. 

Sperm also have acrosomes. These help the sperm identify the female reproductive cells and also contain certain enzymes that help penetrate the membrane that covers the egg.

Therefore, the acrosomes provide a lot of help in order for the sperm to fertilize the egg. 

Another very important adaptation is the amines that the sperm contains. These amines are responsible for the alkaline nature of the seamen, which is basic.

The amines present are ones such as spermine and cadaverine. As the vaginal canal is acidic, the basic alkaline of the semen protects the sperm and the DNA within it. 

As mentioned earlier, each sperm cell contains mitochondria within the midpiece, with each sperm cell containing around 70 mitochondria.

This is what provides the sperm cell with energy, enabling it to propel and reach the egg, so it can fertilize it.

These mitochondria are then rejected ones the head of the sperm reaches the egg. 

Microscopy

Microscopy is how you can analyze cells and their makeup. You can do this using a wet mount or staining method. 

For the wet mount method, you’ll need a sperm sample, a compound microscope, a warm extender, a microscope slide that has been pre-warmed, and a coverslip. 

In order to prepare to analyze your sample, you are to dilute it in the extender (or warm buffered saline).

Then place approximately 20 ul of your sample mixture onto the glass slide of your microscope. 

Once the mixture has been placed on the slide, cover it with the appropriate cover slide. Then you can mount it and begin to analyze your sample! 

This method of analysis will allow you to view the sperm motility and form of these sperm cells. It is also an ideal method to analyze live cells. 

Another method you can use is the staining method.

While this will allow you to differentiate and make it easier to see different areas of the sperm cell, it is a method that will kill the cells. 

This procedure involves immersing the samples into a spermac stain and then viewing them through a microscope.

The stained slides are then viewed under oil immersion or bright light in order to analyze results. 

This is a simple way to analyze all parts of the sperm and identify any issues with them. 

Final Thoughts 

In summary, sperm is constantly being produced in the male body, and the process from when the sperm cells begin to develop to when they are fully mature takes around 74 days. 

The function of sperm is to fertilize an egg, but this may not happen if the sperm quality is low.

There are many factors that could be contributing to this, and while there are some natural remedies to try, you should always seek the advice of a qualified fertility specialist if you are having trouble conceiving. 

Frequently Asked Questions

Are Semen And Sperm The Same Thing? 

Semen and sperm are not the same thing. Semen refers to the ejaculate that exits through the urethra of the penis once a male has been sexually stimulated. 

This is a white fluid that contains sperm among other things, such as other fluids that come from the prostate.

This liquid is also filled with other aspects such as proteins, sugars, and vitamins. 

How Much Semen Is Usually Ejaculated?

The average male will typically ejaculate around a teaspoons worth of semen. However, there are several factors that will contribute to this. 

Semen volume is subject to a few factors of the individual, such as their diet, genetics, health, and smoking. 

Age is also a factor, and studies have shown that males in their early 30s ejaculate the most semen. 

Another factor is how long the individual has gone without intercourse or sexual pleasure.

If they have not experienced this for some time, then when they finally do, they will ejaculate more semen. 

Does The Male Body Every Stop Producing Sperm? 

The male body is constantly producing sperm. As long as the individual is alive, their body will be constantly producing sperm. 

The quality of the sperm, however, will often decline with age, especially after the age of 50.  

What Is The Purpose Of Semen? 

Although healthy sperm have the ability to move and swim, they cannot reach their desired location without help from the semen. 

The semen is what propels the sperm cells through the vaginal canal, and it is here that the sperm cells can begin to swim.

Therefore, semen is an essential part of sperm cells getting to work. 

Are There Any Sperm In Pre-ejaculation? 

While there usually aren’t any sperm cells in pre-ejaculate, there sometimes can be. 

There can sometimes be some leftover sperm in the urethra from the last ejaculation, and this can get mixed together with the pre-ejaculate. 

How Do You Know If Your Sperm Is Healthy?

Healthy sperm usually has a few key characteristics. These include, quantity, movement, and shape. 

A healthy quantity is usually a sperm count of around 15 million sperm cells in every millileter of semen.

When it comes to movement, healthy sperm should be able to swim enough in order to reach the egg to fertilize it.

In regard to their shape, this can carry, but healthy sperm should have a rounded head, a midsection, and a strong tail. 

You can check whether your sperm is healthy in a fertility clinic. Here, you will provide your doctor with a sample of your semen, and they will analyze it for you.

Jennifer Dawkins