The Semen Production Complex Process


You might have never thought about this before, but semen isn’t just simply produced in the testicles. In fact, the process involves your brain, your endocrine system and the autonomic nervous system, as well as your testicles. In a sense, it takes a village to produce semen, and the village in this scenario is your entire body.

It All Starts in the Brain

The process starts in your brain, in an area called the hypothalamus. The hypothalamus is attached to a gland called the pituitary gland. This pea-sized gland is known as the master gland because it directly produces, or initiates the production of, every hormone in your body. Hormones are like the body’s messengers. They are essentially the way that different parts of your body communicate with one another.

The Hormones at Play

There are a number of hormones involved in semen production. The three hormones we’ll talk about are the Gonadotropin-Releasing Hormone (GnRH), the Luteinizing Hormone (LH), and the Follicle Stimulating Hormone (FSH).

The semen production process begins when the hypothalamus secretes GnRH, causing the pituitary gland to release both LH and FSH. The body begins to produce GnRH during puberty.

Semen ProductionThe Testicular Message

Once LH and FSH are released, they go to the testes where they effectively send a message to specialized cells located there: Leydig and Sertoli cells. When the Leydig cells receive the LH message from the pituitary gland, they begin to convert cholesterol into testosterone.

The Role of Testosterone

You’ve probably heard of testosterone, but you may not know what it is exactly and what it does. Basically, it’s another hormone — that is, another messenger — that enters the Sertoli cells. Once testosterone enters these Sertoli cells, it triggers cell division known as mitosis and meiosis.

Cell Division and Sperm Development

You might remember something about mitosis and meiosis from high school biology. These are the processes of cell division. With mitosis, you basically get a clone of the “parent” cell, and this is the division process that every cell in your body goes through, except for the sex cells — that is, the sperm and the egg. The cell division that produces sperm and an egg is known as meiosis.

With meiosis, instead of a clone of the parent cell, the “daughter” cells produced by this process only have one-half of the genetic material that the parent cell had.

Creating Spermatozoa

When sperm is created, stem cells in the Sertoli cells first divide by mitosis. They then begin the process of meiosis, and the resulting spermatozoa (the technical name for sperm) begins to mature.

The Role of Seminiferous Tubules

As with any baby, infant sperm have to have the proper environment to mature. The incubation chambers for these baby sperm are called seminiferous tubules. The walls of these tubules are lined with mucus, and this is where the Sertoli cells attach. The Sertoli cells actually form a tight tissue barrier that keeps harmful products, like bacteria, from entering the incubation chamber, and it keeps fluids inside the chamber from leaking out. This tight barrier is called the Blood-Testis Barrier (BTB).

Semen ProductionMaintaining Testosterone Concentration

It’s important to keep a concentrated level of testosterone in the fluid within the incubation chamber for the sperm to mature. The problem is that much of the liquid in the chamber is water, and testosterone is liposoluble, meaning it concentrates in fat rather than water. That means it would be difficult to achieve the levels of concentration necessary for testosterone to keep the developing sperm healthy were it not for the other hormone we mentioned, FSH. FSH enters the Sertoli cells and causes them to release a protein called the Androgen Binding Protein (ABP). That binds the testosterone molecules so that it can remain highly concentrated in the watery liquid of the tubules.

Temperature Regulation

All of this activity in your seminiferous tubules requires a specific temperature to occur. That’s why the testicles are located externally. If they were up inside the body, the temperature would be too high, so they must hang outside the body in the wrinkled scrotal sac. It’s wrinkled because it needs to adapt — stretch out and relax again — as the muscles within the testes contract and relax in an effort to regulate the temperature.

If it’s a warm day, the testicles hang lower, and if it’s cold outside, they are pulled up closer to the body so that their temperature will always remain at around 93.2 degrees Fahrenheit (34 degrees Celsius), the ideal temperature for sperm production to occur. This is lower than the normal body temperature of 98.6 degrees Fahrenheit (37 degrees Celsius), which is why they can’t be inside the body.

Semen ProductionThe Final Stages

The product of this activity is a fully formed “spermatozoon” with a head, a body, and a tail. We’re still not done, though, because we don’t yet have semen. To understand how we get semen, we must understand the erection and ejaculation process.

Leave a Reply