SEMINIFEROUS TUBULES: FUNCTIONS, STRUCTURE AND TYPES - ANATOMY AND PHYSIOLOGY

The seminiferous tubules are tiny channels located in the testes, where the germination, maturation and transport of sperm take place towards the testicular network.

The seminiferous tubes occupy between 85 and 90% of the volume of the testes, and they fulfill a predominantly exocrine function in the male reproductive system. They are located, specifically, inside the testicular lobes. Each lobes contains between 1 and 5 seminiferous tubes, approximately 70mm long and 0.2mm wide.

Structure

These structures are lined by two types of cells:

Germ cells or spermatogonia

These types of cells are found in the walls of the seminiferous tubules, which are composed of several layers.

Basically, these cells produce sperm after going through the processes of mitosis (reproduction of cells) and meiosis (division of cells), respectively.

The support cells of Sertoli

They are also found in the interior of the seminiferous tubules, surrounding the germ cells.

The sustainable cells of Sertoli complement the nutrition and development of the sperm. They also increase the presence of testosterone in the seminiferous tubules.

For its part, testosterone, which is the male sex hormone, is produced by Leydig cells, which are located in the connective tissue that holds the seminiferous tubules together.

Around the outer surface of the seminiferous tubules is the tunica propria, also called the limiting layer.

This section is made up of a connective tissue made up, in turn, of myoid cells. These cells, when constrained, facilitate the movement of testicular fluid and sperm through each seminiferous tubule.

Types of seminiferous tubules

Two types of seminiferous tubules are distinguished, depending on the function they fulfill within the testicular structure:

Convoluted seminiferous tubules

They are coiled in the lobes of the testicular network, and it is within these structures that the spermatogenesis process takes place; that is, the process of formation of sperm.

Straight seminiferous tubules

They contribute to the transport of the sperm produced in the convoluted seminiferous tubes, from the mediastinum to the testicular network, also known as the rete testis or Haller's network.

This last process is called spermiation. Later, the sperm produced and expelled by the seminiferous tubules are transferred through the testicular network to the vas deferens.

From there, the journey to the epididymis continues, where the spermiogenesis process takes place; that is, the structural formation of the sperm through the allocation of the acrosome.

The acrosome, located in the head of the sperm, in turn contains an important portion of hydrolytic enzymes, essential for the fertilization process.

The seminiferous tubules are extremely important elements within the male reproductive system. If these ducts fail, sperm formation, as well as testosterone production, would be impossible.

In short, thanks to these small conduits, the sperm production process is feasible, and consequently, the reproductive functions that make fertilization and the generation of life possible among human beings.

References

Harrison, R. (1998). Human reproductive system. Encyclopædia Britannica, Inc. London, UK. Recovered from: britannica.com
Seminiferous tubules (2006). Recovered from: innerbody.com
Seminiferous tubules (2014). Recovered from: histologia-testicular.webnode.es
Wikipedia, The Free Encyclopedia (2017). Seminiferous tubules. Recovered from: es.wikipedia.org

SEMINIFEROUS TUBULES: FUNCTIONS, STRUCTURE AND TYPES - ANATOMY AND PHYSIOLOGY - 2025