Male Reproductive Structures
Douglas Wilkin, Ph.D.
Jean Brainard, Ph.D.
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Printed: December 4, 2014
AUTHORS
Douglas Wilkin, Ph.D.
Jean Brainard, Ph.D.
www.ck12.org
C HAPTER
Chapter 1. Male Reproductive Structures
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Male Reproductive
Structures
• Identify male reproductive structures and their functions.
• Describe the role of the testes, the epididymis, and the vas deferens.
Would you believe the male reproductive structures are over 100 feet long?
The male reproductive system has two goals: to produce and deliver sperm and to secrete testosterone. Might seem
simple. But there are a number of complicated processes and structures - including over 100 feet of tubules - that go
into these simple goals.
Male Reproductive Structures
The reproductive system in both males and females consists of structures that produce reproductive cells, or gametes,
and secrete sex hormones. A gamete is a haploid cell that combines with another haploid gamete during fertilization.
Recall that haploid cells have one complete set of chromosomes; in humans that would be 22 autosomes and one sex
chromosome.
Sex hormones are chemical messengers that control sexual development and reproduction. The male reproductive
system consists of structures that produce male gametes called sperm and secrete the male sex hormone testosterone.
The main structures of the male reproductive system are shown in Figure 1.1. Locate them in the figure as you
read about them below. You can also watch an animation about male reproductive structures at this link: http://w
ww.medindia.net/animation/male_reproductive_system.asp .
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FIGURE 1.1
Male Reproductive Structures. Organs of
the male reproductive system include the
penis, testes, and epididymis.
Several
ducts and glands are also part of the
system. Do you know the reproductive
functions of any of these structures?
Penis
The penis is an external genital organ with a long shaft and enlarged tip called the glans penis. The shaft of the penis
contains erectile tissues that can fill with blood and cause an erection. When this occurs, the penis gets bigger and
stiffer. The urethra passes through the penis. Sperm pass out of the body through the urethra. (During urination,
the urethra carries urine from the bladder.)
Testes
The two testes (singular, testis) are located below the penis. They hang between the thighs in a sac of skin called the
scrotum. Each testis contains more than 30 meters (over 90 feet) of tiny, tightly packed tubules called seminiferous
tubules. These tubules are the functional units of the testes. They produce sperm and secrete testosterone.
Epididymis
The seminiferous tubules within each testis join to form the epididymis. The epididymis (plural, epididymis) is a
coiled tube about 6 meters (20 feet) long lying atop the testis inside the scrotum. The functions of the epididymis
are to mature and store sperm until they leave the body.
Ducts and Glands
In addition to these organs, the male reproductive system consists of a series of ducts and glands. Ducts include the
vas deferens and ejaculatory ducts. They transport sperm from the epididymis to the urethra in the penis. Glands
include the seminal vesicles and prostate gland. They secrete substances that become part of semen.
Semen
Semen is the fluid that carries sperm through the urethra and out of the body. In addition to sperm, it contains
secretions from the glands. The secretions control pH and provide sperm with nutrients for energy.
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Chapter 1. Male Reproductive Structures
Summary
• The male reproductive system consists of structures that produce sperm and secrete testosterone.
• Male reproductive structures include the penis, testes, and epididymis.
Explore More
Review
1.
2.
3.
4.
What is a gamete?
What are sex hormones?
What are the two major roles of the male reproductive system?
Name two male reproductive organs and identify their functions.
References
1. Laura Guerin. Structures of the male reproductive system.. CC BY-NC 3.0
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