Testicle
Diagram of testicles
Latin	testis
Gray's	subject #258 1236
Artery	Testicular artery
Vein	Testicular vein, Pampiniform plexus
Nerve	Spermatic plexus
Lymph	Lumbar lymph nodes
Dorlands/Elsevier	t_05/12799705

The testicle (from Latin testis, meaning "witness",^[1] plural testes) is the male generative gland in animals. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Gray's Anatomy the Respiratory apparatus ( Apparatus Respiratorius Respiratory system Respiratory apparatus Arteries are Blood vessels that carry blood away from the Heart. The testicular artery (the male Gonadal artery, also called the internal spermatic arteries in older texts is a branch of the Abdominal aorta that supplies In the Circulatory system, a vein is a Blood vessel that carries Blood back toward the Heart (as opposed to Artery, a blood vessel The testicular vein (or spermatic vein) the male Gonadal vein, carries deoxygenated blood from its corresponding Testis to the Inferior vena cava The Spermatic veins emerge from the back of the Testis, and receive tributaries from the Epididymis: they unite and form a convoluted plexus the plexus pampiniformis A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons. The spermatic plexus (or testicular plexus) is derived from the Renal plexus, receiving branches from the Aortic plexus. The lymphatic system in Vertebrates is a network of conduits that carry a clear fluid called Lymph. The lumbar lymph nodes (paraaortic nodes are a group of Lymph nodes residing in the Lumbar region Elsevier, the world's largest Publisher of Medical and Scientific literature, forms part of the Reed Elsevier group Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. In linguistics grammatical number is a Grammatical category of nouns pronouns and adjective and verb agreement that expresses count distinctions (such as "one" The gonad is the organ that makes Gametes The gonads in males are the Testes and the gonads in Females are the Ovaries. This article will concentrate on mammalian testicles unless otherwise noted.

Anatomy and physiology

Function

Like the ovaries (to which they are homologous), testicles are components of both the reproductive system (being gonads) and the endocrine system (being endocrine glands). "Ovaria" redirects here This is also a proposed section and a Synonym of Solanum. In Evolutionary biology, homology has come to mean any similarity between characters that is due to their shared ancestry. The reproductive system is a system of organs within an Organism which work together for the purpose of Reproduction. The gonad is the organ that makes Gametes The gonads in males are the Testes and the gonads in Females are the Ovaries. The endocrine system is an integrated system of small organs that involve the release of extracellular signaling molecules known as Hormones The endocrine system is instrumental Endocrine glands are Glands that secrete their product ( Hormones, directly into the blood rather than through a duct The respective functions of the testicles are;

• producing sperm (spermatozoa)
• producing male sex hormones that of which testosterone is the best-known

Both functions of the testicle, sperm-forming and endocrine, are under control of gonadotropic hormones produced by the anterior pituitary:

• luteinizing hormone (LH)
• follicle-stimulating hormone (FSH)

External appearance

A human scrotum, containing the testicles. A spermatozoon or spermatozoan ( pl spermatozoa) from the Ancient Greek σπέρμα (seed and ζῷον (living being and more commonly known An organism's sex is defined by the gametes it produces males produce male gametes (spermatozoa or Sperm) while females produce female gametes (ova or Egg cells; individual Hormones (from Greek ὁρμή - "impetus" are chemicals released by cells that affect cells in other parts of the body Testosterone is a Steroid hormone from the Androgen group In mammals testosterone is primarily secreted in the testes of males and the Ovaries The pituitary gland, or hypophysis, is an Endocrine gland about the size of a Pea. Luteinizing hormone ( LH, also known as lutropin) is a Hormone produced by the Anterior pituitary gland. Follicle-stimulating hormone ( FSH) is a Hormone synthesized and secreted by Gonadotropes in the Anterior pituitary gland. In some Male Mammals the scrotum - also 'scrutum' or 'scrootum' - is a protuberance of Skin and Muscle containing the Testicles

Male mammals have two testicles, which are often contained within an extension of the abdomen called the scrotum. Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands In Vertebrates such as Mammals the abdomen (belly constitutes the part of the body between the Thorax (chest and Pelvis. In some Male Mammals the scrotum - also 'scrutum' or 'scrootum' - is a protuberance of Skin and Muscle containing the Testicles In mammals with external testicles it is most common for one testis to hang lower than the other. It is estimated that in about 85% of men the lower hanging testicle is the left one. This is due to differences in the vascular anatomical structure on the right and left sides.

In normal adult human males, testicular size ranges from the lower end of around 14 cm³ to the upper end larger than 92cm³. Measurement in the living adult is done in two basic ways:

• comparing the testicle with ellipsoids of known sizes (orchidometer). An ellipsoid is a type of quadric surface that is a higher dimensional analogue of an Ellipse. An orchidometer is a Medical instrument used to measure the Volume of the Testicles The orchidometer was introduced in 1966 by pediatric
• measuring the length, depth and width with a ruler, a pair of calipers or ultrasound imaging. Not to be confused with Supersonic. Ultrasound is cyclic Sound pressure with a Frequency greater than the upper

The volume is then calculated using the formula for the volume of an ellipsoid: 4/3 π × (length/2) × (width/2) × (depth/2). An ellipsoid is a type of quadric surface that is a higher dimensional analogue of an Ellipse.

To some extent, it is possible to change testicular size. Short of direct injury or subjecting them to adverse conditions, e. g. , higher temperature than they are normally accustomed to, they can be shrunk by competing against their intrinsic hormonal function through the use of externally administered steroidal hormones. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Steroids taken for muscle enhancement often have the undesired side effect of testicular shrinkage. Similarly, stimulation of testicular functions via gonadotropic-like hormones may enlarge their size. Gonadotropins are Protein Hormones secreted by Gonadotrope cells of the Pituitary gland of Vertebrates Gonadotropin is sometimes Testicles may shrink or atrophy during hormone replacement therapy. Hormone replacement therapy may refer to Hormone replacement therapy (menopause Hormone replacement therapy (female-to-male

Internal structure

Transverse section through the left side of the scrotum and the left testis.

Duct system

Histological section through testicular parenchyma of a boar. 1 Lumen of Tubulus seminiferus contortus, 2 spermatids, 3 spermatocytes, 4 spermatogonia, 5 Sertoli cell, 6 Myofibroblasts, 7 Leydig cells, 8 capillaries

Under a tough membraneous shell, the tunica albuginea, the testis contains very fine coiled tubes called the seminiferous tubules. Seminiferous tubules are located in the Testicles and are the specific location of Meiosis, and the subsequent creation of gametes, namely Spermatozoa The term spermatid refers to the Haploid male Gametid that results from division of secondary Spermatocytes As a result of Meiosis, each spermatid A spermatocyte is a Male Gametocyte which is derived from a Spermatogonium. A spermatogonium (plural spermatogonia) is an intermediary male Gametogonium (a kind of Germ cell) in the production of Spermatozoa. A Sertoli cell (a kind of Sustentacular cell) is a 'nurse' cell of the testes which is part of a Seminiferous tubule. A Myofibroblast is a cell that is in between a Fibroblast and a Smooth muscle cell in differentiation Leydig cells, also known as interstitial cells of Leydig, are found adjacent to the Seminiferous tubules in the testicle. Capillaries are the smallest of a body's Blood vessels measuring 5-10 μm in diameter which connect Arterioles and Venules and enable the interchange Seminiferous tubules are located in the Testicles and are the specific location of Meiosis, and the subsequent creation of gametes, namely Spermatozoa The tubes are lined with a layer of cells that, from puberty into old-age, produce sperm cells. The term sperm is derived from the Greek word (σπέρμα sperma (meaning "seed" and refers to the male reproductive cells. The sperm travel from the seminiferous tubules to the rete testis located in the mediastinum testis, to the efferent ducts, and then to the epididymis where newly-created sperm cells mature (see spermatogenesis). Rete testis is an anastomosing network of delicate Tubules located in the hilum of the Testicle ( Mediastinum testis) that carries sperm The mediastinum testis is a network of fibrous connective tissue that extends from the upper to near the lower extremity of the Testis, and is wider above than below The efferent ducts (or efferent ductules or ductuli efferentes) connect the Rete testis with the initial section of the Epididymis. The epididymis is part of the Human Male Reproductive system and is present in all male Mammals It is a narrow tightly-coiled Tube Spermatogenesis is the process by which male Spermatogonia develop into mature Spermatozoa. The sperm move into the vas deferens, and are eventually expelled through the urethra and out of the urethral orifice through muscular contractions. The vas deferens (plural vasa deferentia also called ductus deferens, ( Latin: "carrying-away vessel" is part of the Male Anatomy In Anatomy, the urethra (from Greek ουρήθρα - ourethra) is a tube which connects the Urinary bladder to the outside of

Between the seminiferous tubules are special cells called Leydig cells (or "interstitial cells") where testosterone and other androgens are formed. Leydig cells, also known as interstitial cells of Leydig, are found adjacent to the Seminiferous tubules in the testicle. Testosterone is a Steroid hormone from the Androgen group In mammals testosterone is primarily secreted in the testes of males and the Ovaries Androgen is the generic term for any natural or synthetic compound usually a Steroid Hormone, that stimulates or controls the development and maintenance of masculine

Blood supply and lymphatic drainage

Blood supply and lymphatic drainage of the testes and scrotum are distinct:

• The paired testicular arteries arise directly from the abdominal aorta and descend through the inguinal canal, while the scrotum and the rest of the external genitalia is supplied by the internal pudendal artery (itself a branch of the internal iliac artery). The lymphatic system in Vertebrates is a network of conduits that carry a clear fluid called Lymph. The testicular artery (the male Gonadal artery, also called the internal spermatic arteries in older texts is a branch of the Abdominal aorta that supplies The abdominal aorta is the largest Artery in the Abdominal cavity. The inguinal canal is a passage in the anterior (toward the front of the body abdominal wall which in men conveys the Spermatic cord and in women the round ligament The internal pudendal artery is an Artery that branches off the Internal iliac artery, providing blood to the External genitalia. The internal iliac artery (formerly known as the hypogastric artery) is the main Artery of the Pelvis.
• Lymphatic drainage of the testes follows the testicular arteries back to the paraaortic lymph nodes, while lymph from the scrotum drains to the inguinal lymph nodes. The paraaortic lymph nodes (also known as para-aortic, periaortic, and peri-aortic) are a group of Lymph nodes that lie in front of the lumbar

Layers

Many anatomical features of the adult testis reflect its developmental origin in the abdomen. In Vertebrates such as Mammals the abdomen (belly constitutes the part of the body between the Thorax (chest and Pelvis.

The layers of tissue enclosing each testicle are derived from the layers of the anterior abdominal wall. The abdominal wall represents the boundaries of the Abdominal cavity. Notably, the cremasteric muscle arises from the internal oblique muscle. The cremaster muscle is a Muscle that covers the testis. Contraction Its function is to raise and lower the Scrotum in order to regulate The internal oblique muscle (of the abdomen is the intermediate muscle of the abdomen lying just underneath the External oblique and just above (superficial to the Transverse

The blood-testis barrier

Large molecules cannot pass from the blood into the lumen of a seminiferous tubule due to the presence of tight junctions between adjacent Sertoli cells. Tight junctions, or zonula occludens, are the closely associated areas of two cells whose membranes join together forming a virtual impermeable barrier A Sertoli cell (a kind of Sustentacular cell) is a 'nurse' cell of the testes which is part of a Seminiferous tubule. The spermatogonia are in the basal compartment (deep to the level of the tight junctions) and the more mature forms such as primary and secondary spermatocytes and spermatids are in the adluminal compartment.

The function of the blood-testis barrier (red highlight in diagram above) may be to prevent an auto-immune reaction. The blood-testis barrier (abbreviated as BTB is a physical barrier between the Blood vessels and the Seminiferous tubules of the animal testes. Autoimmunity is the failure of an organism to recognize its own constituent parts as self, which results in an immune response against its own cells and tissues Mature sperm (and their antigens) arise long after immune tolerance is established in infancy. An antigen (from antibody-generating) or immunogen is a substance that prompts the generation of Antibodies and can cause an immune response Therefore, since sperm are antigenically different from self tissue, a male animal can react immunologically to his own sperm. In fact, he is capable of making antibodies against them.

Injection of sperm antigens causes inflammation of the testis (autoimmune orchitis) and reduced fertility. Thus, the blood-testis barrier may reduce the likelihood that sperm proteins will induce an immune response, reducing fertility and so progeny.

Temperature regulation

The testes work best at temperatures slightly less than core body temperature (36. 6 °C or 98. The Celsius Temperature scale was previously known as the centigrade scale. 6 °F for humans). Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 The spermatogenesis is less efficient at lower and higher temperatures. Spermatogenesis is the process by which male Spermatogonia develop into mature Spermatozoa. There are a number of mechanisms to maintain the testes at the optimum temperature.

Cremasteric muscle

The cremasteric muscle is part of the spermatic cord. The cremaster muscle is a Muscle that covers the testis. Contraction Its function is to raise and lower the Scrotum in order to regulate The spermatic cord is the name given to the cord-like structure in males formed by the Vas deferens and surrounding tissue that run from the Abdomen down to each When this muscle contracts, the cord is shortened and the testicle is moved closer up toward the body, which provides slightly more warmth to maintain optimal testicular temperature. When cooling is required, the cremasteric muscle relaxes and the testicle is lowered away from the warm body and is able to cool. This phenomenon is known as the cremasteric reflex. The cremasteric reflex is a cutaneous Reflex observed It also occurs in response to stress (the testicles rise up toward the body in an effort to protect them in a fight). There are persistent reports that relaxation indicates approach of orgasm. There is a noticeable tendency to also retract during orgasm.

The testicles can also be lifted voluntarily using the pubococcygeus muscle, which partially activates related muscles. The pubococcygeus muscle or PC muscle is a hammock-like muscle found in both sexes that stretches from the Pubic bone to the Coccyx (tail bone forming This can sometimes be triggered by tightening or sucking in the stomach or abdomen.

Development

There are two phases in which the testicles grow substantially, namely in embryonic and pubertal age.

Embryonic

During mammalian development, the gonads are at first capable of becoming either ovaries or testes. "Ovaria" redirects here This is also a proposed section and a Synonym of Solanum. ^[2] In humans, starting at about week 4 the gonadal rudiments are present within the intermediate mesoderm adjacent to the developing kidneys. Intermediate mesoderm is a type of Mesoderm that is located between the Paraxial mesoderm and the Lateral plate. At about week 6, sex cords develop within the forming testes. In Animal Embryology, the sex cords (or primitive sex cords) are structures that develop from the Gonadal ridge. These are comprised of early Sertoli cells that surround and nurture the germ cells that migrate into the gonads shortly before sex determination begins. Germ cells are progenitors of the Gametes. These singled out cells move through the gut to the developing Gonads and undergo mitotic proliferation followed In males, the sex-specific gene SRY that is found on the Y-chromosome initiates sex determination by downstream regulation of sex-determining factors, (such as GATA4, SOX9 and AMH), which leads to development of the male phenotype, including directing development of the early bipotential gonad down the male path of development. SRY ( Sex-determining Region Y) is a Sex -determining Gene on the Y chromosome in the Therians (placental mammals and marsupials

Pubertal

The testicles grow in response to the start of spermatogenesis. Spermatogenesis is the process by which male Spermatogonia develop into mature Spermatozoa. Size depends on lytic function, sperm production (amount of spermatogenisis present in testis), interstitial fluid, and Sertoli cell fluid production. Interstitial fluid (or tissue fluid) is a solution which bathes and surrounds the cells of multicellular animals A Sertoli cell (a kind of Sustentacular cell) is a 'nurse' cell of the testes which is part of a Seminiferous tubule. After puberty, the volume of the testicles can be increased by over 500% as compared to the pre-pubertal size. In humans the average testicle size after puberty measures up to around 2 inches long, 0. 8 inch in breadth, and 1. 2 inches in height (5 x 2 x 3 cm). Testicles are fully descended before one reaches puberty.

Evolution

External testicles

The basal condition for mammals is to have internal testicles. Only the Boreoeutherian land mammals, the large group of mammals that includes humans, have externalized testicles. Boreoeutheria (synonymous with Boreotheria) is a Clade that is composed of the sister Taxa Laurasiatheria and Euarchontoglires ( Indeed their testicles function best at temperatures lower than their core body temperature. Their testes are located outside of the body, suspended by the spermatic cord within the scrotum. The testes of the non-boreotherian mammals such as the monotremes, armadillos, sloths, elephants remain within the abdomen. ^[3] There are also some Boreoeutherian mammals with internal testes, such as the rhinoceros.

Marine boreotherian mammals such as whales and dolphins, also have internal testes, but it has recently been shown (e. g. , for dolphins) that they use elaborate vascular networks to provide the necessary temperature lowering for optimum function. As external testes would increase drag, many boreotherian aquatic mammals have internal testes which are kept cool by special circulatory systems that cool the arterial blood going to the testes by placing the arteries near veins bringing cooled venous blood from the skin.

There are several hypotheses why most boreotherian mammals have external testes which operate best at a temperature that is slightly less than the core body temperature, e. g. that it is stuck with enzymes evolved in a colder temperature due to external testes evolving for different reasons, that the lower temperature of the testes simply is more efficient for sperm production.

1) More efficient. The classic hypothesis is that cooler temperature of the testes allows for more efficient fertile spermatogenesis. Spermatogenesis is the process by which male Spermatogonia develop into mature Spermatozoa. In other words, there are no possible enzymes operating at normal core body temperature that are as efficient as the ones evolved, at least none appearing in our evolution so far.

The early mammals had lower body temperatures and thus their testes worked efficiently within their body. However it is argued that boreotherian mammals have higher body temperatures than the other mammals and had to develop external testicles to keep them cool. It is argued that those mammals with internal testicles, such as the monotremes, armadillos, sloths, elephants, and rhinoceroses, have a lower core body temperatures than those mammals with external testicles.

However, the question remains why birds despite having very high core body temperatures have internal testes and did not evolve external testes. ^[4] It was once theorized that birds used their air sacs to cool the testes internally, but later studies revealed that birds' testes are able to function at core body temperature. ^[4].

Some mammals which have seasonal breeding cycles keep their testes internal until the breeding season at which point their testes descend and increase in size and become external^[5].

2) Irreversible adaptation to sperm competition. It has been suggested that the ancestor of the boreoeutherian mammals was a small mammal that required very large testes (perhaps rather like those of a hamster) for sperm competition and thus had to place its testes outside the body. Hamsters are Rodents belonging to the Subfamily Cricetinae. The subfamily contains about 18 Species, classified in six or seven genera Sperm competition is " competition between Sperm of two or more Males for the Fertilization of an Ovum " (Parker 1970 ^[6] This led to enzymes involved in spermatogenesis, spermatogenic DNA polymerase beta and recombinase activities evolving an unique temperature optimum, slightly less than core body temperature. When the boreoeutherian mammals then diversified into forms that were larger and/or did not require intense sperm competition they were stuck with enzymes that operated best at cooler temperatures and had to keep their testicles outside the body. This position is made less parsimonious by the fact that the kangaroo, a non-boreoeutherian mammal, has external testicles. A kangaroo is a Marsupial from the family Macropodidae (macropods meaning 'large foot' The ancestors of kangaroos might, separately from boreotherian mammals, have also been subject to heavy sperm competition and thus developed external testes, however, kangaroo external testicles are suggestive of a possible adaptive function for external testes in large animals.

3) Protection from abdominal cavity pressure changes. One argument for the evolution of external testes is that it protects the testes from abdominal cavity pressure changes caused by jumping and galloping. ^[7]

Testicular size

Testicular size as a proportion of body weight varies widely. In the mammalian kingdom, there is a tendency for testicular size to correspond with multiple mates (e. g. , harems, polygamy). The term polygamy (a Greek word meaning "the practice of multiple marriage" is used in related ways in Social anthropology, Sociobiology, and Production of testicular output sperm and spermatic fluid is also larger in polygamous animals, possibly a spermatogenic competition for survival. The term polygamy (a Greek word meaning "the practice of multiple marriage" is used in related ways in Social anthropology, Sociobiology, and Sperm competition is " competition between Sperm of two or more Males for the Fertilization of an Ovum " (Parker 1970 The testicles of the right whale are likely to be the largest of any animal, each weighing around 500 kg (1,100 lb). Right whales are the species of large Baleen whales belonging to the Genus Eubalaena.

Health issues

The testicles are well-known to be very sensitive to impact and injury. Blue balls is a slang term for a temporary fluid congestion in the testicles and prostate region caused by prolonged sexual arousal. Blue balls is the Slang term for a congested prostate or Vasocongestion, the condition of temporary fluid congestion in the Testicles and Prostate The testicle (from Latin testiculus, diminutive of testis, meaning "witness" virility plural testes) is the male The prostate (from Greek προστάτης - prostates, literally "one who stands before" "protector" "guardian" is a

The most prominent diseases of testicles are:

• testicular cancer and other neoplasms
• swelling of a testicle, caused by hydrocele testis
• inflammation of the testicles, called orchitis
• inflammation of the epididymis, called epididymitis
• retention cyst of a tubule of the rete testis or the head of the epididymis, called spermatocele
• spermatic cord torsion also called testicular torsion
• varicocele — swollen vein from the testes, usually affecting the left testicle^[8]
• anorchidism is the absence of one or both testicles. Testicular cancer is Cancer that develops in the Testicles a part of the Male reproductive system A hydrocele testis is an accumulation of clear fluid in the Tunica vaginalis, the most internal of membranes containing a Testicle. Orchitis is an often very painful condition of the Testicles involving inflammation swelling and frequently infection Epididymitis is a medical condition in which there is Inflammation of the Epididymis (a curved structure at the back of the Testicle in which Rete testis is an anastomosing network of delicate Tubules located in the hilum of the Testicle ( Mediastinum testis) that carries sperm The epididymis is part of the Human Male Reproductive system and is present in all male Mammals It is a narrow tightly-coiled Tube Spermatocele is a Retention Cyst of a Tubule of the Rete testis or the head of the Epididymis distended with a milky fluid that contains In testicular torsion the Spermatic cord that provides the blood supply to a Testicle is twisted cutting off the blood supply often causing Orchalgia. In testicular torsion the Spermatic cord that provides the blood supply to a Testicle is twisted cutting off the blood supply often causing Orchalgia. Varicocele is an abnormal enlargement of the Veins in the Scrotum draining the Testicles.

The removal of one or both testicles is termed:

• Inguinal orchiectomy, in medicine (where orchiectomy and orchectomy are synonymous), and
• castration in general use, especially when done as punishment or torture, or as a catch-all term for orchidectomy in a veterinary context. Inguinal orchiectomy is a relatively minor surgical procedure to remove a Testicle. Castration (also referred to as Gelding, Neutering, Fixing, orchiectomy, and orchidectomy is any action surgical, chemical Castration (also referred to as Gelding, Neutering, Fixing, orchiectomy, and orchidectomy is any action surgical, chemical Veterinary medicine the application of medical, diagnostic, and therapeutic principles to companion, domestic, exotic, wildlife
• Gelding in the specifically equine sense. A gelding is a castrated animal &mdash in English the term specifically refers to a castrated male Horse or other Equine such as a Donkey

Testicular prostheses are available to mimic the appearance and feel of one or both testicles, when absent as from injury or as treatment for gender identity disorder. Gender identity disorder (GID is the formal diagnosis used by Psychologists and Physicians to describe persons who experience significant gender dysphoria (discontent There have also been some instances of their implanting in dogs

Other testicular issues:

• Cryptorchidism or "undescended testicles", when the testicle does not descend into the scrotum of the infant boy. Cryptorchidism is the absence of one or both Testes from the Scrotum.
• Retractile testicle, when the testicle occasionally moves up into the lower abdomen as the cremaster muscle contracts. In Vertebrates such as Mammals the abdomen (belly constitutes the part of the body between the Thorax (chest and Pelvis. The cremaster muscle is a Muscle that covers the testis. Contraction Its function is to raise and lower the Scrotum in order to regulate ^[9]

As food

Main article: Animelles

Testicles are eaten as food in many parts of the world. Animelles is the culinary term for a type of Offal, the Testicles of animals especially young rams when used as food

Additional images

Testicle of a cat:	1: Extremitas capitata, 2: Extremitas caudata, 3: Margo epididymalis, 4: Margo liber, 5: Mesorchium, 6: Epididymis, 7: testicular artery and vene, 8: Ductus deferens	Testis surface	Testis cross section
The right testis, exposed by laying open the tunica vaginalis.

See also

• Anorchia
• cryptorchidism (cryptorchismus)
• Polyorchidism
• infertility
• List of homologues of the human reproductive system
• orchidometer
• spermatogenesis
• sterilization (surgical procedure), vasectomy
• Epididymis
• Spermatic cord
• Penis
• Sperm
• Ovary
• Geier Hitch
• Bollocks
• WikiSaurus:testicles — the WikiSaurus list of synonyms and slang words for testicles in many languages

References