NationMaster - Encyclopedia: Spermatozoon

A spermatozoon or spermatozoan (pl. spermatozoa), from the ancient Greek σπέρμα (seed) and ζῷον (living being) and more commonly known as a sperm cell, is the haploid cell that is the male gamete. It joins an ovum to form a zygote. A zygote is a single cell, with a complete set of chromosomes, that normally develops into an embryo. Image File history File links Sperm-egg. ... A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ... This article is about fertilisation in animals and plants. ... Image File history File links Complete_diagram_of_a_human_spermatozoa. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... Beginning of Homers Odyssey The Ancient Greek language is the historical stage of the Greek language[1] as it existed during the Archaic (9thâ€“6th centuries BC) and Classical (5thâ€“4th centuries BC) periods in Ancient Greece. ... Ploidy is the number of homologous sets of chromosomes in a biological cell. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... A gamete (from Ancient Greek Î³Î±Î¼ÎµÏ„Î·Ï‚; translated gamete = wife, gametes = husband) is a cell that fuses with another gamete during fertilization (conception) in organisms that reproduce sexually. ... Categories: Biology stubs ... A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ... It has been suggested that Biparental zygote be merged into this article or section. ... For other uses, see Embryo (disambiguation). ...

Sperm cells contribute half of the genetic information to the diploid offspring. In mammals, the sex of the offspring is determined by the sperm cells: a spermatozoon bearing a Y chromosome will lead to a male (XY) offspring, while one bearing an X chromosome will lead to a female (XX) offspring (the ovum always provides an X chromosome). Sperm cells were first observed by a student of Antoni van Leeuwenhoek in 1677.^[1] For other uses, see Gene (disambiguation). ... Diploid (meaning double in Greek) cells have two copies (homologs) of each chromosome (both sex- and non-sex determining chromosomes), usually one from the mother and one from the father. ... This article or section does not cite its references or sources. ... A scheme of a condensed (metaphase) chromosome. ... This article is about the Male sex. ... For other uses, see Female (disambiguation). ... A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ... Anton van Leeuwenhoek Anton van Leeuwenhoek (October 24, 1632 - August 30, 1723, full name Thonius Philips van Leeuwenhoek (pronounced Layewenhook) was a Dutch tradesman and scientist from Delft, Netherlands. ... 1677 (MDCLXXVII) was a common year starting on Friday of the Gregorian calendar (or a common year starting on Monday of the 10-day slower Julian calendar). ...

Mammalian spermatozoan structure, function, and size

Humans

The human sperm cell is the reproductive cell in males. Sperm cells come in two types; "male" and "female." Sperm cells that give rise to female (XX) offspring after fertilization differ in that they carry an X chromosome, while sperm cells that give rise to male (XY) offspring carry a Y chromosome. The "female" sperm cell also differs phenotypically in that it has a larger head in comparison to the "male" sperm cell.

In male humans, sperm cells consists of a head 5 µm by 3 µm and a tail 50 µm long. The Reynolds number associated with spermatozoa is in the order of 1×10^-2, so it is known that the spermatozoa exhibit laminar flow. Spermatozoan stream lines are straight and parallel. The tail flagellates, which propels the sperm cell (at about 1-3 mm/minute in humans) by whipping in an elliptical cone. ^[2]. Semen has an alkaline nature, and they do not reach full motility (hypermotility) until they reach the vagina where the alkaline pH is neutralized by acidic vaginal fluids. This gradual process takes 20-30 minutes. In this time, fribinogen from the seminal vesicles forms a clot, securing and protecting the sperm. Just as they become hypermotile, fibrinolysin from the prostate dissolves the clot, allowing the sperm to progress optimally. A micrometre (American spelling: micrometer, symbol Âµm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... In fluid mechanics, the Reynolds number may be described as the ratio of inertial forces (vsÏ) to viscous forces (Î¼/L) and, consequently, it quantifies the relative importance of these two types of forces for given flow conditions. ... Laminar flow (bottom) and turbulent flow (top) over a submarine hull. ... Flagellata from Ernst Haeckels Artforms of Nature, 1904 Parasitic excavate (Giardia lamblia) Green alga (Chlamydomonas) Flagellates are cells with one or more whip-like organelles called flagella. ... The vagina, (from Latin, literally sheath or scabbard ) is the tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. ... Categories: Stub | Andrology | Exocrine system | Reproductive system ... // Basic Information Fibrinolysin is an enzyme derived from plasma of bovine origin or extracted from cultures of certain bacteria. ... The prostate is a compound tubuloalveolar exocrine gland of the male mammalian reproductive system. ...

The spermatozoon is characterized by a minimum of cytoplasm and the most densely packed DNA known in eukaryotes. Compared to mitotic chromosomes in somatic cells, sperm DNA is at least sixfold more highly condensed.^[3] Schematic showing the cytoplasm, with major components of a typical animal cell. ... Mitosis divides genetic information during cell division. ... This article does not cite any references or sources. ...

During fertilization, the sperm's mitochondria are destroyed by the egg cell, and this means only the mother is able to provide the baby's mitochondria and mitochondrial DNA, which have an important application in tracing maternal ancestry. However it has been recently discovered that mitochondrial DNA can be recombinant ^[4]. In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... Mitochondrial DNA (some captions in German) Mitochondrial DNA (mtDNA) is the DNA located in organelles called mitochondria. ... Kinship and descent is one of the major concepts of cultural anthropology. ...

Avoidance of immune system response

Glycoprotein molecules on the surface of sperm cells are recognised by all human immune systems, and interpreted as a signal that the cell should not be rejected. The male immune system might otherwise attack sperm whilst in the testes, and the female immune system would attack sperm in the reproductive tract. The specific glycoproteins coating sperm cells are also utilised by some cancerous and bacterial cells, some parasitic worms, and HIV-infected white blood cells, in order to avoid an immune response from the host organism.^[5] N-linked protein glycosylation (N-glycosylation of N-glycans) at Asn residues (Asn-x-Ser/Thr motifs) in glycoproteins[1]. Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to their polypeptide backbones. ... In biology, a host is an organism that harbors a parasite, mutual partner, or commensal partner, typically providing nourishment and shelter. ...

Spermatozoa in other organisms

Image File history File links Size of this preview: 300 Ã— 600 pixelsFull resolution (301 Ã— 602 pixel, file size: 31 KB, MIME type: image/png) Motile plant and algae sperm cells. ... Image File history File links Size of this preview: 300 Ã— 600 pixelsFull resolution (301 Ã— 602 pixel, file size: 31 KB, MIME type: image/png) Motile plant and algae sperm cells. ... For other uses, see Sperm (disambiguation). ...

Animals

The fruit fly^[3] has the largest known spermatozoon relative to its size. Drosophila melanogaster produces sperm that can be up to 1.8 mm in size, which is longer than the adult fly. The incredibly long tail is thought to block other sperm from entering the egg. The entire sperm, tail included, gets incorporated into the oocyte cytoplasm.^[6] Fruit fly may refer to: Tephritidae, the family of large fruit flies. ... Binomial name Meigen, 1830[1] Drosophila melanogaster (from the Greek for black-bellied dew-lover) is a two-winged insect that belongs to the Diptera, the order of the flies. ... An oocyte or ovocyte is a female gametocyte or germ cell involved in reproduction. ... Schematic showing the cytoplasm, with major components of a typical animal cell. ...

Sea urchins such as Arbacia punctulata—are the workhorses of sperm research, because they spawn large numbers of sperm into the sea, making them well-suited as model organisms for research experiments. Slate pencil urchin (cidaroid) Group of black, long-spined Caribbean sea urchins, Diadema antillarum (Philippi) Sea urchin roe. ...

Plants, algae and fungi

The gametophytes of bryophytes, ferns and some gymnosperms produce motile sperm cells, contrary to pollen grains employed in most gymnosperms and all angiosperms. This renders sexual reproduction in the absence of water impossible, since water is a necessary medium for sperm and egg to meet. Algae and lower plant sperm cells are often multi-flagellated (see image) and thus morphologically different from animal spermatozoa. In plants that undergo alternation of generations, a gametophyte is the structure, or phase of life, that contains only half of the total complement of chromosomes: The sporophyte produces spores, in a process called meiosis. ... The bryophytes are those embryophytes (land plants) that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. ... This article is about the group of pteridophyte plants. ... Divisions Pinophyta (or Coniferophyta) - Conifers Ginkgophyta - Ginkgo Cycadophyta - Cycads Gnetophyta - Gnetum, Ephedra, Welwitschia The gymnosperms (Gymnospermae) are a group of spermatophyte seed-bearing plants with ovules on the edge or blade of an open sporophyll, the sporophylls usually arranged in cone-like structures. ... For other uses, see Sperm (disambiguation). ... SEM image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis). ... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants (also angiosperms or Magnoliophyta) are one of the major groups of modern plants, comprising those that produce seeds in specialized reproductive organs called flowers, where the ovulary or carpel is enclosed. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ...

Some algae and fungi produce non-motile sperm cells, called spermatia. In higher plants and some algae and fungi, fertilization involves the migration of the sperm nucleus through a fertilization tube (e.g. pollen tube in higher plants) to reach the egg cell. Pollen may refer to the microspores of either angiosperms (flowering plants) or gymnosperms (conifers and cycads). ...

Spermatozoa production in mammals

Spermatozoa are produced in the seminiferous tubules of the testes in a process called spermatogenesis. Round cells called spermatogonia divide and differentiate eventually to become spermatozoa. During copulation the cloaca or vagina gets inseminated, and then the spermatozoa move through chemotaxis to the ovum inside a Fallopian tube or the uterus. Cross section of the epithelium of a seminiferous tubule showing various stages of spermatocyte development Spermatogenesis is the process by which male spermatogonia develop into mature spermatozoa. ... This article needs to be wikified. ... Human male anatomy The testicles, known medically as testes (singular testis), are the male generative glands in animals. ... The introduction of this article does not provide enough context for readers unfamiliar with the subject. ... A pair of lions copulating in the Maasai Mara, Kenya. ... In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, urinary, and genital tracts of certain animal species. ... The vagina, (from Latin, literally sheath or scabbard ) is the tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. ... Insemination is the introduction of semen into the genital tract of a female. ... Chemotaxis is a kind of taxis, in which bodily cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. ... The Fallopian tubes, also known as oviducts, uterine tubes, and salpinges (singular salpinx) are two very fine tubes leading from the ovaries of female mammals into the uterus. ... This article is about female reproductive anatomy. ...

The acrosome reaction

Mammalian sperm cells become even more active when they approach an egg cell. They swim faster and their tail movements become more forceful and erratic. This behaviour is called "hyperactivation." In sperm cells of many higher animals, the acrosome develops over the anterior half of its head. ... Image File history File links Merge-arrow. ... In sperm cells of many higher animals, the acrosome develops over the anterior half of its head. ... Image File history File links Acrosome_reaction_diagram. ... Image File history File links Acrosome_reaction_diagram. ... Subclasses Subclass Perischoechinoidea Order Cidaroida (pencil urchins) Subclass Euechinoidea Superorder Atelostomata Order Cassiduloida Order Spatangoida (heart urchins) Superorder Diadematacea Order Diadematoida Order Echinothurioida Order Pedinoida Superorder Echinacea Order Arbacioida Order Echinoida Order Phymosomatoida Order Salenioida Order Temnopleuroida Superorder Gnathostomata Order Clypeasteroida (sand dollars) Order Holectypoida Wikispecies has information related to...

A recent discovery links hyperactivation to a sudden influx of calcium ion into the tails. The whip-like tail (flagellum) of the sperm is studded with ion channels formed by proteins called CatSper. These channels are selective, allowing only calcium ion to pass. The opening of CatSper channels is responsible for the influx of calcium. The sudden rise in calcium levels causes the flagellum to form deeper bends, propelling the sperm more forcefully through the viscous environment. Sperm hyperactivity is necessary for breaking through two physical barriers that protect the egg from fertilization. Ion channels are pore-forming proteins that help to establish and control the small voltage gradient that exists across the plasma membrane of all living cells (see cell potential) by allowing the flow of ions down their electrochemical gradient. ... Cation channels of sperm: This small family of ion channels, normally referred to as Catsper channels or CatSper, is related to the two-pore channels and distantly related to TRP channels. ...

The first barrier to sperm is made up of so-called cumulus cells embedded in a gel-like substance made primarily of hyaluronic acid. The cumulus cells develop in the ovary with the egg and support it as it grows.

The second barrier coating the oocyte is a thick shell formed by glycoproteins called the zona pellucida. One of the proteins that make up the zona pellucida binds to a partner molecule on the sperm. This lock-and-key type mechanism is species-specific and prevents the sperm and egg of different species from fusing. There is some evidence that this binding is what triggers the acrosome to release the enzymes that allow the sperm to fuse with the egg. An oocyte or ovocyte is a female gametocyte or germ cell involved in reproduction. ... The zona pellucida (or zona striata in older texts) is a glycoprotein membrane surrounding the plasma membrane of an oocyte. ... In spermatozoa of many animals, the acrosome is an organelle that develops over the anterior half of the spermatozoons head. ...

When a sperm cell reaches the egg the acrosome releases its enzymes. These enzymes weaken the shell, allowing the sperm cell to penetrate it and reach the plasma membrane of the egg. Part of the sperm's cell membrane then fuses with the egg cell's membrane, and the contents of the head sink into the egg. Categories: Biology stubs ...

Upon penetration, the oocyte is said to have become activated. It undergoes its secondary meiotic division, and the two haploid nuclei (paternal and maternal) fuse to form a zygote. In order to prevent polyspermy and minimise the possibility of producing a triploid zygote, several changes to the egg's cell membranes renders them impenetrable shortly after the first sperm enters the egg. It has been suggested that Biparental zygote be merged into this article or section. ... In biology, Polyspermy describes an egg that has been fertilized by more than one sperm. ... Polyploid (in Greek: Ï€Î¿Î»Î»Î±Ï€Î»ÏŒÎ½ - multiple) cells or organisms contain more than two copies (ploidy) of their chromosomes. ...

References

Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 96th day of the year (97th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... December 17 is the 351st day of the year (352nd in leap years) in the Gregorian calendar. ...

External links

Image File history File links Commons-logo. ... This article is about human male reproductive system. ... A pictorial illustration of the human female reproductive system. ... In some male mammals the scrotum is a protuberance of skin and muscle containing the testicles. ... The dartos is a layer of smooth muscular fiber. ... The external spermatic fascia (intercrural or intercolumnar fascia) is a thin membrane, prolonged downward around the surface of the cord and testis. ... The cremaster muscle is a muscle that covers the testis. ... As the cremaster descends, it forms a series of loops which differ in thickness and length in different subjects. ... The internal spermatic fascia (infundibuliform fascia) is a thin layer, which loosely invests the cord; it is a continuation downward of the transversalis fascia. ... The perineal raphe extends from the anus, through the mid-line of the scrotum (scrotal raphe) and upwards through the posterior mid-line aspect of the penis (penile raphe). ... Male Anatomy The spermatic cord is the name given to the cord-like structure formed by the vas deferens and surrounding tissue (veins, arteries, nerves, and lymphatic vessels) that run from the abdomen down to each testicle. ... Look up testes in Wiktionary, the free dictionary. ... This page meets Wikipedias criteria for speedy deletion. ... For other structures with the same name, see Tunica albuginea. ... The Appendix testis is a vestigial remnant of the MÃ¼llerian duct present on on the upper testis attached to the tunica vaginalis about 90% of the time. ... The mediastinum testis extends from the upper to near the lower extremity of the gland, and is wider above than below. ... The glandular structure of the testis consists of numerous lobules. ... Each lobule of the testis is contained in one of the intervals between the fibrous septa which extend between the mediastinum testis and the tunica albuginea, and consists of from one to three, or more, minute convoluted tubes, the tubuli seminiferi. ... Leydig cells, also known as interstitial cells of Leydig, are found adjacent to the seminiferous tubules in the testes. ... A Sertoli cell (a kind of sustentacular cell) is a nurse cell of the testes which is part of a seminiferous tubule. ... The blood-testis barrier (abbreviated as BTB) is a barrier between the blood vessels and the seminiferous tubules of the animal testes. ... Cross section of the epithelium of a seminiferous tubule showing various stages of spermatocyte development Spermatogenesis is the process by which male spermatogonia develop into mature spermatozoa. ... A Spermatogonium (plural: spermatogonia) is an intermediary male gametogonium (a kind of germ cell) in the production of spermatozoa. ... Spermatocytogenesis is the male form of gametocytogenesis. ... Spermatogenesis refers to the creation, or genesis, of sperm cells, which occurs in the male gonads or testes. ... it is the creation of spermatids from secondary spermatocytes through mitosis ... The term spermatid refers to the haploid male germ cell that results from secondary spermatocyte division. ... Spermiogenesis is the creation of a spermatozoon from a spermatid. ... Human male anatomy The testicles, known medically as testes (singular testis), are the male generative glands in animals. ... The tubuli seminiferi recti (or tubuli recti, or straight seminiferous tubules) enter the fibrous tissue of the mediastinum, and pass upward and backward, forming, in their ascent, a close net-work of anastomosing tubes which are merely channels in the fibrous stroma, lined by flattened epithelium, and having no proper... Rete testis is an anastomosing network of delicate tubules located in the hilum of the testicle (mediastinum testis) 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. ... On the head of the epididymis is a second small stalked appendage (sometimes duplicated); it is named the appendix of the epididymis (pedunculated hydatid), and is usually regarded as a detached efferent duct. ... The vas deferens (plural: vasa deferentia), also called ductus deferens, (Latin: carrying-away vessel) is part of the male anatomy of some species, including humans. ... At the fundus of the bladder the ductus deferens becomes enlarged and tortuous, and this portion is termed the ampulla. ... The Ejaculatory ducts are part of the human male anatomy, which cause the reflex action of ejaculation. ... The internal urethral orifice is placed at the apex of the trigonum vesicae, in the most dependent part of the bladder, and is usually somewhat crescentic in form; the mucous membrane immediately behind it presents a slight elevation, the uvula vesicae, caused by the middle lobe of the prostate. ... In anatomy, the urethra is a tube which connects the urinary bladder to the outside of the body. ... The prostatic urethra, the widest and most dilatable part of the canal, is about 3 cm. ... The intermediate part of male urethra (membranous portion) is the shortest, least dilatable, and, with the exception of the external orifice, the narrowest part of the canal. ... The spongy urethra (cavernous portion of urethra, penile urethra) is the longest part of the urethra, and is contained in the corpus cavernosum urethraeÃ¦. It is about 15 cm. ... The cavernous portion of the urethra is narrow, and of uniform size in the body of the penis, measuring about 6 mm. ... Nathan J. Youngers favorite peice of candy to suck on. ... The seminal vesicles are a pair of simple tubular glands posterinferior to the urinary bladder of males. ... Each seminal vesicle consists of a single tube, coiled upon itself, and giving off several irregular cecal diverticula; the separate coils, as well as the diverticula, are connected together by fibrous tissue. ... The prostate is a compound tubuloalveolar exocrine gland of the male mammalian reproductive system. ... Upon the posterior wall of the prostatic urethra is a narrow longitudinal ridge, the urethral crest, formed by an elevation of the mucous membrane and its subjacent tissue. ... At the forepart of the urethral crest, below its summit, is a median elevation, the seminal colliculus, upon or within the margins of which are the following: the orifices of the prostatic utricle the slit-like openings of the ejaculatory ducts. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The Ejaculatory ducts are part of the human male anatomy, which cause the reflex action of ejaculation. ... On either side of the urethral crest is a slightly depressed fossa, the prostatic sinus, the floor of which is perforated by numerous apertures, the orifices of the prostatic ducts from the lateral lobes of the prostate. ... The prostatic ducts (or prostatic ductules) open into the floor of the prostatic portion of the urethra, and are lined by two layers of epithelium, the inner layer consisting of columnar and the outer of small cubical cells. ... A bulbourethral gland (or Cowpers gland) is one of two small exocrine glands present in the reproductive system of human males. ... The penis (plural penises, penes) is an external male sexual organ. ... The root of the penis is triradiate in form, consisting of the diverging crura, one on either side, and the median urethral bulb. ... For their anterior three-fourths the corpora cavernosa penis lie in intimate apposition with one another, but behind they diverge in the form of two tapering processes, known as the crura, which are firmly connected to the rami of the pubic arch. ... Just before each crus of the penis meets its fellow it presents a slight enlargement, named by Kobelt the bulb of the corpus cavernosum penis. ... The fundiform ligament is a specialization of the superficial (Scarpas) fascia of the abdomen. ... In males, the suspensory ligament of the penis is attached to the pubic symphysis, which holds the penis close to the pubic bone and supports it when erect. ... The body of the penis extends from the root to the ends of the corpora cavernosa penis, and in it these corpora cavernosa are intimately bound to one another. ... A corpus cavernosum is one of a pair of a sponge-like regions of erectile tissue which contain most of the blood in the male penis during erection. ... Corpus spongiosum (Plural: Corpora Spongiosa) (also known as corpus cavernosum urethrae in older texts) is the mass of spongy tissue surrounding the male urethra within the penis. ... The glans penis (or simply glans) is the sensitive tip of the penis. ... The foreskin or prepuce (a technically broader term that also includes the clitoral hood, the homologous structure in women) is a retractable double-layered fold of skin and mucous membrane that covers the glans penis and protects the urinary meatus when the penis. ... The word frenulum on its own is often used for the frenulum of prepuce of penis, which is an elastic band of tissue under the glans penis that connects to the prepuce, or foreskin to the vernal mucosa, and helps contract the prepuce over the glans. ... The circumference of the base of the glans forms a rounded projecting border, the corona of the glans penis, overhanging a deep retroglandular sulcus, behind which is the neck of the penis. ... Fascia is specialized connective tissue layer which surrounds muscles, bones, and joints, providing support and protection and giving structure to the body. ... The subcutaneous tissue of penis (or superficial penile fascia) is continuous above with the fascia of Scarpa, and below with the dartos tunic of the scrotum and the fascia of Colles. ... Bucks fascia is a layer of deep fascia covering the penis. ... The fibrous envelope of the corpus cavernosum urethrÃ¦ (or tunica albuginea) is thinner, whiter in color, and more elastic than that of the corpora cavernosa penis. ... The corpora cavernosa penis are surrounded by a strong fibrous envelope consisting of superficial and deep fibers. ...

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