Biology

Scrotum and its contents: Testicles

len Alfred Ajibola - Tue, 25th February, 2020 @ 12:18 PM

Topics in Biology

Ecological pyramid explained with its importance and limitations Hindbrain: Medulla Oblongata and its features Food web explained with examples Biology Scheme of Work, SS1, First Term Biology Scheme of Work, SS1, 2nd Term Biology Scheme of Work, SS1, 3rd Term Seminal Vesicles and Bulbourethral Glands as Male Accessory Sex Organs Scrotum and its contents: Testicles Brain: Introduction to the Human Brain Forebrain: Lobes of the Cerebrum and their Functions Cerebellum: Parts and Functions of the Cerebellum Midbrain: Division and Functions of the Midbrain Negative Feedback Mechanism in Homeostasis Arterial Disorders: Characteristics and Causes of Arterial Disorders Types of Desert and their Characteristics Characteristics of Tropical Rainforest Swamp Forest: What are Swamp Forests? Characteristics of Swamp Forests Savanna: Savanna and Grassland explained Savanna - Types of Savanna


Academic Questions in Biology

Please check out our Test Your Knowledge page to see all Questions and Answers

In a food chain, the primary consumers are classified under trophic level  _____.

  • A. Zero

  • B. One

  • C. Two

  • D. Three

  • E. Four

  • F. Five

Cold blooded animals are referred to as _____.

  • A. Homeotherms

  • B. Endotherms

  • C. Poilokitherms

  • D. Ectotherms

  • E. Thermotherms

  • F. None of the above

All reptiles are vertebrates.

  • A. True

  • B. False

_____ cells are responsible for the formation of osteoblasts.

  • A. Osteocytes
  • B. Chondrocytes
  • C. Chondroblasts
  • D. Osteoclasts
  • E. Osteoprogenitor cells
  • F. Osteoblastic

_____ is a bone that constitute the axial skeleton.

  • A. Clavicle
  • B. Scapula
  • C. Patella
  • D. Radius
  • E. Sternum
  • F. Femur

Which of the following is false concerning cartilages and bones?

  • A. Cartilage does not have a direct blood supply while bones have direct blood supply
  • B. The process of ossification replaces a cartilage to bone
  • C. The protein that makes up cartilage is called chondrin while that that makes up bone is called ossein
  • D. Cartilage grows from both ends while bones grow from one of its epiphysis
  • E. They both have living cells within them
  • F. Haversian system is absent in cartilage but present in bones

A diagram showing the movement of energy through a food chain is called a _____.

  • A. Food Chain
  • B. Food Web
  • C. Food Energy
  • D. Food Link
  • E. Food Flow
  • F. Food Pyramid

Which of the following is NOT a part of the wrist bones (or carpal bones)?

  • A. Cuboid
  • B. Scaphoid
  • C. Hamate
  • D. Triquetral
  • E. Pisiform
  • F. Trapezium

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Scrotum and Testicles:

The scrotum or scrotal sac is visible on every male as it lies underneath the penis, hanging from the midline of the pelvic region just between both thighs. It is a part of the male external genitalia.

Please read an introduction to the male reproductive system here.

Inside the scrotal sac are two oval shaped testicles or testes (singular -> testis) which are responsible for the formation and storage of sperm. The process of sperm formation is referred to as spermatogenesis.


  • Sperm is the male gamete in humans and other animals while the egg or ova is the female gamete. You can think of a gamete as the sex cell. The union of both sex cells (sperm + ova) is termed fertilization. A zygote is formed immediately after fertilization. It is this zygote that develops into the embryo, then a foetus (or fetus) and eventually a neonate or newly born child.

The scrotum is located outside the body and that's ideal. This is so because the testis requires a temperature slightly lower than that of the normal body temperature (36.5oC) to properly form the sperm cells. In fact, this is the ideal reason why the testes descends from the abdominal cavity (inside the body) to the scrotum (outside the body). This external position of scrotum therefore presents a temperature reduction by -1oC to -7oC.


The scrotum is divided in its midline by the perineal raphe. The perineal raphe is present in males and females. It is visible as a midline seen on some parts of the human body.

The image below shows the scrotum, its internal contents and the perineal raphe:
Scrotum - Len Academy

You can read on seminal vesicles and bulbourethral glands here.


What are the Testicles?

The testicle is the male reproductive gland in humans (males) and all other male animals. Its primary function is to produce sperm and the male sex hormone 'testosterone'.

Generally, males have two testicles of similar sizes with both located within either half of the scrotum. Interestingly, the scrotal sacs are not always equal in length; and as a result, one of the testicle (or testis) typically extends farther downwards into the scrotum in relation to the other.


Inside the developing male embryo (in the mother's womb), the testicles begin their formation in the abdominal region. After 8 weeks of gestation, the testicles gradually descend from the abdomen into the scrotum via through a tube-like structure in the inguinal canal. For this reason, the testicles are located outside the body (scrotum) and this is crucial for sperm formation or spermatogenesis.


As a male, one may have observed that on cold days, the scrotum hang towards the body. Conversely, it tends to move downwards (away from the body) on warmer days. This is so because at cooler temperatures, the cremaster muscle contracts, moving both testes towards the body with a resultant rise in the scrotal temperature. Conversely, the cremaster muscle relaxes when the environmental temperature rises, ultimately pushing the testes away from the body.

Sperm is produced by the testes present within the scrotum; and the surrounding temperature is extremely important for it's formation. To this end, the cremaster muscles of the scrotum have got a great ability to contract and relax, thus aiding the testes to either move closer to the body or away from it; depending on the surrounding temperature.

Please read on homeostasis here.


Structurally, both testes are covered by a membranous sheet called the tunica albuginea. The testes comprises of very minute and highly coiled tubes called seminiferous tubules. The cells lining the seminiferous produces the male gamete or spermatozoa or sperm cells.

From the seminiferous tubules, the sperm is conveyed into a another tubular structure termed rete testis. The rete testis is located in the mediastinum testis.

Structures of the testes - Len Academy

The sperm cells are conveyed from the rete testis into the ductuli efferentes testis (efferent ducts), and then to the epididymis. The maturation of sperm cells occur in the epididymis.

From the epididymis, the sperm travels into the vas deferens and eventually the spermatic cord. The vas deferens therefore functions to transport sperm from the epididymis to the spermatic cord as they are eventually moved through the urethra and out of the external urethral orifice through a series of muscular contractions.


Meanwhile, understand that sperm and semen aren't the same thing. Sperm is the male sex cell (and it happens to be the smallest cell in the human body). It is exactly what meets and fertilizes the female sex cell (ova or egg). Ironically, the ova is the biggest cell in the human body.

Semen refers to the thick whitish (or slightly yellowish) and viscous fluid released from the penis. The process of releasing semen in males is termed ejaculation.

You can read on amazing facts in biology here.


During ejaculation, millions of sperm cells are introduced into the female’s vagina; and they swim upwards (towards the oviduct or fallopian tube in the female) with the aid of their tail-like structure called flagella.

Ejaculation is always accompanied with a characteristic feeling of pleasure. In fact, this pleasurable feeling is the climax of sexual excitement and it's referred to as orgasm.

Note: The sperm cells are present within the semen. This is shown in the image below:
Sperm vs Semen - Len Academy


In summary, the semen contains the following:

  • Sperm cells

  • Amino acids

  • Enzymes

  • Vitamin C

  • Zinc prostate specific antigen

  • Mucus

  • Prostagladins

  • Phosphatases

  • Silic Acid

  • Flavins

Understand that apart from the sperm cells, many of these components making up the semen are secretions from the male accessory reproductive glands.

Please read on the male accessory sex organs here.


Apart from the testicles, also found in the scrotum are:

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Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.


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NOTABLE POINTS IN Biology

For a thing to be considered living, it must possess all the basic characteristics of life. These include:

  1. Movement

  2. Respiration

  3. Nutrition

  4. Irritability or Sensitivity

  5. Growth

  6. Excretion

  7. Reproduction

  8. Death

  9. Adaptation

  10. Competition

Please read the explanations on all the basic characteristics of life here

During strenuous exercises like sprinting or running, your body may actually work in the shortage of oxygen. During this time, your body owes oxygen (called oxygen debt) and it must be replenished or repayed after the exercise is stopped. This is why you breathe excess of oxygen after you stopped the exercise.

This is the concept of anaerobic respiration

Food Chain - Len Academy

A food chain is a diagram that shows the relationship between plants and animals within a habitat on the basis of how they rely on each other for food.

Note: Habitat is a place where an organism live. It is of three types:

  • Terrestrial (Land)
  • Aquatic (Water)
  • Arboreal (Treetops)

You can read on food chain here

The term Biology originated from two Greek words. They are:

  • Bios: means life.

  • Logos: means knowledge or to study.

Biology can therefore be defined as the study of life

Anything that has life is generally considered as a living organism (or organism). All living organisms must be able to carry the following activities:

  1. Movement

  2. Respiration

  3. Nutrition

  4. Irritability or Sensitivity

  5. Growth

  6. Excretion

  7. Reproduction

  8. Death

  9. Adaptation

  10. Competition

The above listed points are often regarded as the basic characteristics of life. You can memorize them using the acronym -> MR. NIGER DAC.

You can read on the introduction to biology and the basic characteristics of life here

The gas used in the manufacture of food by plants is Carbon dioxide or Carbon(IV)oxide or CO2

Plants manufacture food through a process called photosynthesis.

Please read on photosynthesis here

It is noteworthy to state that plants are the only orgnisms that take away CO2 from the atmosphere