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Encyclopedia > Seminiferous tubules
Human male anatomy

The testicles, known medically as testes (singular testis), are the male generative glands in animals. Male mammals have two testicles, which are often contained within an extension of the abdomen called the scrotum. Image File history File links Drawing of the Male Internal Sexual Anatomy From alt. ... Image File history File links Drawing of the Male Internal Sexual Anatomy From alt. ... The word singular may refer to one of several concepts. ... The gonad is the organ that makes gametes. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Placozoa (trichoplax) Subregnum Bilateria (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (includes extinct ancestors)/Placentalia (excludes extinct ancestors) Afrosoricida Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla Pholidota Plesiadapiformes... In anatomy, the abdomen is a part of the body; in humans, it is the region between the thorax and the pelvis. ... The scrotum (human variant shown) is a thin extension of the abdomen that contains the testes and helps regulate their temperature. ...


In mammals, the testes are located outside of the body, as they are suspended by the spermatic cord and within the scrotum. This is due to the fact that spermatogenesis in mammals is more efficient at a temperature somewhat less than the core body temperature (37°C or 98.6°F for humans). The cremasteric muscle is part of the spermatic cord. 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 the temperature needs to be lowered, the cremasteric muscle relaxes and the testicle is lowered away from the warm body and are able to cool. This phenomenon is known as the cremasteric reflex. It also occurs in response to stress (the testicles rise up toward the body in an evolutionary effort to protect them in a fight) and they also contract during orgasm. Animals other than mammals do not have externalized testicles, Birds despite having very high core body temperatures have internal testis: it was once theorized that birds used their air sacs to cool the testis internally, but later studies revealed that bird’s testis function at core body temperature.[1] Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... Spermatogenesis refers to the creation, or genesis, of spermatozoa, which occurs in the male gonads. ... The degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius (1701–1744), who first proposed a similar system in 1742. ... Fahrenheit is a temperature scale named after the German physicist Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... Cremasteric Reflex is a reflex in males only. ... For other meanings of bird, see bird (disambiguation). ... An air sac is a component of the pulmonary system. ...


It is normal for one testis to hang lower than the other (usually the left). This is primarily due to differences in the vascular anatomical structure on the right and left sides. It is thought that this is another evolutionary development that protects each testis from bouncing off the other.

Look up testes in Wiktionary, the free dictionary.

Contents

Wikipedia does not have an article with this exact name. ... Wiktionary logo Wiktionary is a sister project to Wikipedia intended to be a free wiki dictionary (including thesaurus and lexicon) in every language. ...


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). The respective functions of the testicles are: Human female internal reproductive anatomy Ovaries are egg-producing reproductive organs found in female organisms. ... Two or more structures are said to be homologous if they are alike because of shared ancestry. ... A reproductive systems is the ensembles and interactions of organs and or substances within an organism that stricly pertain to reproduction. ... The gonad is the organ that makes gametes. ... Major endocrine glands. ... An endocrine gland is one of a set of internal organs involved in the secretion of hormones into the blood. ...

Both functions of the testicle, sperm-forming and endocrine, are under control of gonadotropic hormones produced by the anterior pituitary: A sperm cell attempts to penetrate an ovum coat to fertilize it. ... A hormone (from Greek horman - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... Testosterone is a steroid hormone from the androgen group. ... Located at the base of the skull, the pituitary gland is protected by a bony structure called the sella turcica. ...

Luteinizing hormone (LH) is a hormone synthesised and secreted by gonadotropes in the anterior lobe of the pituitary gland. ... Follicle stimulating hormone Follicle stimulating hormone (FSH) is a hormone synthesised and secreted by gonadotropes in the anterior pituitary gland. ...

Structure

Under a tough fibrous shell, the tunica albuginea, the testis contains very fine coiled tubes called the seminiferous tubules. The tubes are lined with a layer of cells that, from puberty into old-age, produce sperm cells. The sperm travel from the seminiferous tubules to the rete testis, the efferent ducts, and then to the epididymis where newly-created sperm cells mature (see spermatogenesis). The sperm move into the vas deferens (also called the ductus deferens), which opens into the urethra. Upon any sufficient sexual arousal, the sperm cells move through the ejaculatory duct and into the prostatic urethra, where the prostate, through muscular contractions, ejaculates the sperm, mixed with other fluids, out through the penis. The tunica albuginea is the tough fibrous covering of the testicles. ... Puberty refers to the process of physical changes by which a childs body becomes an adult body capable of reproduction. ... Rete testis is an anastomosing network of delicate tubules located in the testicular hilum that carries sperm from the seminiferous tubules to the vasa efferentia. ... The efferent ducts are part of the testes and connect the rete testis with the epididymis. ... Male Anatomy The epididymis is part of the human male reproductive system and is present in all male mammals. ... Spermatogenesis refers to the creation, or genesis, of spermatozoa, which occurs in the male gonads. ... Male Anatomy The vas deferens, also called ductus deferens, (Latin: carrying-away vessel) is part of the human male anatomy. ... Female anatomy In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. ... Sexual arousal is the process and state of an animal being ready for sexual intercourse. ... Male Anatomy The Ejaculatory ducts are part of the human male anatomy, which cause the reflex action of ejaculation. ... Male Anatomy The prostate is an exocrine gland of the male mammalian reproductive system. ... The penis (plural penises or penes) or phallus is an external male sexual organ. ...


The genital anatomy described here, along with the neuroanatomy and hormonal systems that enable it to perform ejaculation, have as primary evolutionary functions the impregnation of a fertile female of the same species (or a sufficiently close one), via sexual intercourse with her. Categories: Biological reproduction | Biology stubs ... In biology, a species is the basic unit of biodiversity. ... It has been suggested that Sexual penetration be merged into this article or section. ...

Transverse section through the left side of the scrotum and the left testis. The sac of the tunica vaginalis is represented in a distended condition.
Transverse section through the left side of the scrotum and the left testis. The sac of the tunica vaginalis is represented in a distended condition.

Between the seminiferous tubules are special cells called interstitial cells (Leydig cells) where testosterone and other androgens are formed. Image File history File links Transversetestis. ... Image File history File links Transversetestis. ... Interstitial is a generic term for referring to the space between other structures or objects. ... Testosterone is a steroid hormone from the androgen group. ... 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 characteristics in vertebrates by binding to androgen receptors. ...


Testicular size

Testicular size in relation to body weight varies widely. In the mammalian kingdom, there is a tendency for testicular size to be larger when the species is more likely to be polygamous than monogamous. Production of testicular output is also larger in the polygamous animal, possibly a spermatogenic competition for survival. In normal adult human males, testicular size ranges from the lower end of around 14 cm³ to the upper end larger than 35 cm³. Measurement in the living adult is done in two basic ways: (1) comparing the testicle with ellipsoids of known sizes (orchidometer), or (2) measuring the length, depth and width with a ruler, a pair of calipers or ultrasound imaging. The volume is then calculated, e.g., using the formula for ellipsoids: π/6 × length × width². Usually right and left testicles have about the same size, but not exactly the same size. Polygamy, literally many marriages in ancient Greek, is a marital practice in which a person has more than one spouse simultaneously (as opposed to monogamy where each person has a maximum of one spouse at any one time). ... In monogamy (Greek: monos = single/only and gamos = marriage) a person has only one spouse at a time (as opposed to polygamy). ... Polygamy, literally many marriages in ancient Greek, is a marital practice in which a person has more than one spouse simultaneously (as opposed to monogamy where each person has a maximum of one spouse at any one time). ... Sperm competition is competition between sperm of two or more males for the fertilization of an ova (Parker 1970). ... An orchidometer is a medical instrument used to measure the volume of the testicles. ... A baby in its mothers womb, viewed in a sonogram Ultrasound is sound with a frequency greater than the upper limit of human hearing, approximately 20 kiloHertz/20,000 Hertz. ...


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. Similarly, stimulation of testicular functions via gonadotrophic-like hormones may enlarge their size.


Health issues

The testicles are well-known to be very sensitive to impact and injury. The most important diseases of testicles are: An example of a groin attack, from the 1994 movie On Deadly Ground. ...

The removal of one or both testicles is termed Orchitis is an often very painful condition of the testicles involving inflammation, swelling and frequently infection. ... Testicular cancer is a type of 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. ... Epididymitis is a medical condition where the epididymis becomes inflamed. ... Spermatic Cord Torsion is a swelling in the spermatic cord resulting from an amount of sperms trapped in the canals from the testicles to the scrotum. ... 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 a mass of enlarged veins in the scrotum that develops in the spermatic cord, which leads from the testicles (testes) up through a passageway in the lower abdominal wall (inguinal canal) to the circulatory system. ...

  • orchidectomy, in medicine (where orchiectomy and orchectomy are synonymous), and
  • castration in general use, especially when done for the benefit of others than the subject, for example, to produce a high-voiced castrato from the castration of a pre-pubescent boy

At least for humans, testicular prostheses are available to mimic the appearance and feel of one or both testicles, when absent as from injury or medical treatment. Although these prosthetic testicles mimic the human testicle accurately, many believe the real testicle to be more satisfying. Castration, gelding, neutering, orchiectomy or orchidectomy is any action, surgical or otherwise, by which a biological male loses use of the testes. ... This article does not cite its references or sources. ... A castrato is a male soprano, mezzo-soprano, or alto voice produced either by castration of the singer before puberty or who, because of an endocrinological condition, never reaches sexual maturity. ... Puberty refers to the process of physical changes by which a childs body becomes an adult body capable of reproduction. ...


See also

Reproductive system - edit
Female - Cervix | Clitoris | Clitoral hood | Fallopian tubes | Bartholin's glands | G-spot | Hymen | Labium | Mammary glands | Ovaries | Skene's glands | Urethra | Uterus | Vagina | Vulva
Male - Bulbourethral glands | Ejaculatory duct | Epididymis | Foreskin | Frenulum | Glans penis | Penis | Prostate | Scrotum | Seminal vesicles | Spermatic cord | Testes | Urethra | Vas deferens
Endocrine system - edit
Adrenal gland | Corpus luteum | Hypothalamus | Kidney | Ovaries | Pancreas | Parathyroid gland | Pineal gland | Pituitary gland | Testes | Thyroid gland

  Results from FactBites:
 
Sertoli cell - Wikipedia, the free encyclopedia (458 words)
Transverse section of a tubule of the testis of a rat.
A Sertoli cell (a kind of sustentacular cell) is a 'nurse' cell of the testes which is part of a seminiferous tubule.
The junctions of Sertoli cells form the blood-testis barrier, a structure that partitions the interstitial blood compartment of the testis from the adluminal compartment of the seminiferous tubules.
  More results at FactBites »

 
 

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