Ever wonder what the inside of a male looks like? Find out in this lesson that explores the inner workings of the male reproductive system and the pathway that sperm takes.
When I ask you what makes men and women different, what is the first thing that comes to mind? Well, one of the more obvious answers is they look different. What do I mean by that? Well, males have a penis on the outside and women don’t, right? And while that is correct, there is a little bit more to that answer. Sure, males and females differ on the outside, but what about on the inside? In this lesson, you will learn about what internal structures make a male different from a female.
First, I want to address the purpose of these uniquely male structures. Why do males have testes and other structures that aren’t present in females? Well, one of the instinctual drives in all species is to reproduce – to pass on their genes to future generations. To do this, they have to have a way of packaging, storing and passing on their DNA to those offspring.They do this by producing cells called gametes – haploid germ cells of males and females. Gametes are produced during meiosis and contain half of the parental chromosome. Now, each gender is going to produce its own gamete with only half of its genetic material. In females, they are called eggs, and in males, they are called sperm.
During reproduction, the male gamete combines with the female gamete to produce offspring that has half the DNA of the mom and half the DNA of the dad, giving it its own unique and complete set of DNA. In this lesson, we will focus on the male and the structures used in getting his gamete, sperm, ready for reproduction. The sperm of the male is produced and transported in structures completely different from those found in the female.
So what are these structures? Well, first and foremost we have the testes, or testis (singular). The testes are paired structures in the male whose function is to produce sperm.
Inside each testicle are many tube-like structures where sperm are produced. Once ready, sperm are transported to ducts at the top of the testes that connect to the next structure, called the epididymis. Now, sperm production is just the first step – the sperm that leave the testes are not yet fully mature. They’re almost there but not fully. That is the function of the next structure, called the epididymis.
The epididymis is located on top of each testicle and has two main functions: to store and to mature sperm.
Amazingly, the epididymis is a coiled tubule that, if unwound, would measure about 23 feet! This 23 feet of coiled tube can be divided into 3 parts: the head, the body and the tail. The head of the epididymis is closest to the top of the testes and accepts the immature sperm that is leaving the testes. Once inside the epididymis, the sperm maturation process starts. This process takes about 2 weeks as sperm move from the head, down through the body and into the tail where they are stored until needed.Now, as you look the epididymis, you will notice that both the testes and the epididymis lie outside the main body cavity of the male. Therefore, they need some way to stay connected with the body.
This is where our next structure comes in.
Spermatic Cords and Ductus Deferens
Each epididymis connects to a larger tube called the ductus deferens, also known as the vas deferens, which travels from the epididymis up into the body of the male. Now, running alongside the ductus deferens are arteries and veins, and together these make up paired structures called spermatic cords. It is these cords that connect the testes and the epididymis to the body.
Without these connections, there would be no flow of blood, sperm and other fluids to and from the testes.
In addition to connecting the epididymis to the body, the ductus deferens both stores and transports sperm from the epididymis to the ejaculatory duct, which you will learn about later. It’s kind of like the on-ramp of a highway – it connects the epididymis to the ejaculatory duct, which in turn, merges with the urethra, providing a passageway for sperm to exit the body.
So, let’s take a moment to follow its path:The ductus deferens begins here, at the tail of the epididymis. It then travels up into the abdominal cavity, wraps around the urinary bladder and then curves back down to start its descent behind (or posterior to) the bladder. As it begins its descent, it expands into a portion called the ampulla. The ampulla is part of the ductus deferens and is where most of the sperm is going to be stored until needed.Now you may be asking, why do sperm need to be stored? Why not just make them when they are needed? Well, you see this process of making and maturing sperm actually takes a while, around 2-3 months. So it wouldn’t be very practical to make the sperm as needed, would it? That’s why males have developed places along their reproductive tract to store the sperm that are ready. Ready for what? Well, ready for reproduction! That is where our next set of structures comes in.
Ejaculatory Duct and Urethra
The ampulla joins with ducts from the first set accessory glands to create the ejaculatory duct. Now remember, sperm are stored in the ampulla, so they don’t enter the ejaculatory duct until the male engages in sexual activity. Both the ejaculatory duct and the urethra pass by three accessory glands. Each gland secretes fluids that will nourish and protect sperm as it passes through the male reproductive tract.You can see here that compared to the ductus deferens, the ejaculatory duct is relatively short. That’s because once it passes the first set of accessory glands and enters the second gland, it combines with the urethra.
|This more than two structures to accomplish