Sperm 4

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Sperm 4
Medically Reviewed by Trina Pagano, MD on October 24, 2020
You may know it takes one sperm and one egg to make a baby , but if you're like most folks, you might not remember much else about sperm from biology class. If infertility is an issue for you and your partner, it helps to understand the basics.
The answer depends on a number of things, but the most important is where the sperm are located.
On a dry surface, such as clothing or bedding, sperm are dead by the time the semen has dried. In water, such as a warm bath or hot tub, they'll likely live longer because they thrive in warm, wet places. But the odds that sperm in a tub of water will find their way inside a woman's body and cause them to get pregnant are extremely low.
When sperm are inside women's body, they can live for up to 5 days. If you're a man and you have sex even a few days before your partner ovulates, there's chance they may get pregnant.
How many sperm do you need to get pregnant?
It takes just one sperm to fertilize a woman's egg. Keep in mind, though, for each sperm that reaches the egg, there are millions that don't.
On average, each time men ejaculate they release nearly 100 million sperm. Why are so many sperm released if it takes only one to make a baby? To meet the waiting egg, semen must travel from the vagina to the fallopian tubes, a tough journey that few sperm survive. Experts believe this process may be nature's way of allowing only the healthiest sperm to fertilize the egg, to provide the best chances of having a healthy baby .
For those sperm that complete the trip, getting into the egg, which is covered by a thick layer, is far from a sure thing.
Is there anything you can do to improve the health of your sperm?
Many of the things you do to keep yourself healthy can also do the same for sperm. Try some of these tips:
It's a test that can help your doctor figure out why you and your partner are having trouble having a baby.
Some things you can learn from the analysis:
Amount and thickness of semen. On average, each time men ejaculate they release 2-6 milliliters (mL) of semen, or around a 1/2 teaspoon to 1 teaspoon.
Less than that amount may not contain enough sperm for a woman to get pregnant. On the other hand, more than that could dilute the concentration of sperm.
Semen should be thick to start with and become thinner 10 to 15 minutes after ejaculation. Semen that stays thick may make it difficult for sperm to move.
Sperm concentration. Also called sperm density, this is the number of sperm in millions per milliliter of semen. Fifteen million or more sperm per mL is considered normal.
Sperm motility. This is the percentage of sperm in a sample that are moving, as well as an assessment of how they move. One hour after ejaculation, at least 32% of sperm should be moving forward in a straight line.
Morphology. This is an analysis of the size, shape, and appearance of sperm.
Do men stop making sperm when they're older?
Men can continue to be fertile throughout life. The amount of sperm you make goes down as you get older, but even elderly men have fathered children.
University of California, Santa Barbara, SexInfo Online: "How Long Can Sperm Live in Air? In a Bath?" "Semen;" and "Making Strong Sperm."
WomensHealth.gov: "Trying to Conceive."
Oakland University: "Dr. Lindemann's Sperm Facts."
University of Michigan Health System: "Male Infertility."
Lab Tests Online: "Semen Analysis."
MedlinePlus.gov: "Aging changes in the male reproductive system."
IVFMD.com: "New World Health Semen Analysis Parameters."
How much do you know about conception?
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WebMD does not provide medical advice, diagnosis or treatment.

From Wikipedia, the free encyclopedia
Male reproductive cell in anisogamous forms of sexual reproduction
For other uses, see Sperm (disambiguation) .
Further information: Sperm donation
This article relies largely or entirely on a single source . Relevant discussion may be found on the talk page . Please help improve this article by introducing citations to additional sources . Find sources: "Sperm" – news · newspapers · books · scholar · JSTOR ( August 2021 )
This section needs expansion . You can help by adding to it . ( August 2021 )


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^ Hewitson, Laura & Schatten, Gerald P. (2003). "The biology of fertilization in humans" . In Patrizio, Pasquale; et al. (eds.). A color atlas for human assisted reproduction: laboratory and clinical insights . Lippincott Williams & Wilkins. p. 3. ISBN 978-0-7817-3769-2 . Retrieved 2013-11-09 .

^ Semen and sperm quality

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^ Cyranoski, David (2016). "Researchers claim to have made artificial mouse sperm in a dish". Nature . doi : 10.1038/nature.2016.19453 . S2CID 87014225 .

^ Gurevich, Rachel (2008-06-10). "Does Age Affect Male Fertility?" . About.com . Retrieved 14 February 2010 .

^ Gavriliouk D, Aitken RJ (2015). "Damage to Sperm DNA Mediated by Reactive Oxygen Species: Its Impact on Human Reproduction and the Health Trajectory of Offspring". The Male Role in Pregnancy Loss and Embryo Implantation Failure . Advances in Experimental Medicine and Biology. Vol. 868. pp. 23–47. doi : 10.1007/978-3-319-18881-2_2 . ISBN 978-3-319-18880-5 . PMID 26178844 .

^ Marchetti F, Wyrobek AJ (2008). "DNA repair decline during mouse spermiogenesis results in the accumulation of heritable DNA damage" . DNA Repair . 7 (4): 572–81. doi : 10.1016/j.dnarep.2007.12.011 . PMID 18282746 . S2CID 1316244 .

^ Marchetti F, Essers J, Kanaar R, Wyrobek AJ (2007). "Disruption of maternal DNA repair increases sperm-derived chromosomal aberrations" . Proceedings of the National Academy of Sciences of the United States of America . 104 (45): 17725–9. Bibcode : 2007PNAS..10417725M . doi : 10.1073/pnas.0705257104 . PMC 2077046 . PMID 17978187 .

^ Marchetti F, Bishop J, Gingerich J, Wyrobek AJ (2015). "Meiotic interstrand DNA damage escapes paternal repair and causes chromosomal aberrations in the zygote by maternal misrepair" . Scientific Reports . 5 : 7689. Bibcode : 2015NatSR...5E7689M . doi : 10.1038/srep07689 . PMC 4286742 . PMID 25567288 .

^ Lüpold, Stefan; Manier, Mollie K; Puniamoorthy, Nalini; Schoff, Christopher; Starmer, William T ; Luepold, Shannon H. Buckley; Belote, John M; Pitnick, Scott (2016). "How sexual selection can drive the evolution of costly sperm ornamentation" . Nature . 533 (7604): 535–8. Bibcode : 2016Natur.533..535L . doi : 10.1038/nature18005 . PMID 27225128 . S2CID 4407752 .

^ Gardiner, Jennifer R (2016). "The bigger, the better" . Nature . 533 (7604): 476. doi : 10.1038/533476a . PMID 27225117 .

^ Sarfraz Manzoor (2 November 2012). "Come inside: the world's biggest sperm bank" . The Guardian . Retrieved 4 August 2013 .

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^ Fiedler, Anja; Rehdorf, Jessica; Hilbers, Florian; Johrdan, Lena; Stribl, Carola; Benecke, Mark (2008). "Detection of Semen (Human and Boar) and Saliva on Fabrics by a Very High Powered UV-/VIS-Light Source" . The Open Forensic Science Journal . 1 : 12–15. doi : 10.2174/1874402800801010012 .

^ Allery, J. P; Telmon, N; Mieusset, R; Blanc, A; Rougé, D (2001). "Cytological detection of spermatozoa: Comparison of three staining methods". Journal of Forensic Sciences . 46 (2): 349–51. doi : 10.1520/JFS14970J . PMID 11305439 .

^ Illinois State Police/President's DNA Initiative. "The Presidents's DNA Initiative: Semen Stain Identification: Kernechtrot" (PDF) . Archived from the original (PDF) on 2016-12-26 . Retrieved 2009-12-10 .

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Wikimedia Commons has media related to Sperm .
Sperm is the male reproductive cell , or gamete , in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum , which are known as spermatozoa , while some red algae and fungi produce non-motile sperm cells, known as spermatia . [1] Flowering plants contain non-motile sperm inside pollen , while some more basal plants like ferns and some gymnosperms have motile sperm. [2]

Sperm cells form during the process known as spermatogenesis , which in amniotes ( reptiles and mammals ) takes place in the seminiferous tubules of the testes . [3] This process involves the production of several successive sperm cell precursors, starting with spermatogonia , which differentiate into spermatocytes . The spermatocytes then undergo meiosis , reducing their chromosome number by half, which produces spermatids . The spermatids then mature and, in animals, construct a tail, or flagellum, which gives rise to the mature, motile sperm cell. This whole process occurs constantly and takes around 3 months from start to finish.

Sperm cells cannot divide and have a limited lifespan, but after fusion with egg cells during fertilisation , a new organism begins developing, starting as a totipotent zygote . The human sperm cell is haploid , so that its 23 chromosomes can join the 23 chromosomes of the female egg to form a diploid cell with 46 paired chromosomes. In mammals , sperm is stored in the epididymis and is released from the penis during ejaculation in a fluid known as semen .

The word sperm is derived from the Greek word σπέρμα , sperma , meaning "seed".

It is generally accepted that isogamy is the ancestor to sperm and eggs. However, there are no fossil records for the evolution of sperm and eggs from isogamy leading there to be a strong emphasis on mathematical models to understand the evolution of sperm. [4]

A widespread hypothesis states that sperm evolved rapidly, but there is no direct evidence that sperm evolved at a fast rate or before other male characteristics. [5]

The main sperm function is to reach the ovum and fuse with it to deliver two sub-cellular structures: (i) the male pronucleus that contains the genetic material and (ii) the centrioles that are structures that help organize the microtubule cytoskeleton . [ clarification needed ]

The mammalian sperm cell can be divided in 2 parts:

The neck or connecting piece contains one typical centriole and one atypical centriole such as the proximal centriole-like . [10] [11] The midpiece has a central filamentous core with many mitochondria spiralled around it, used for ATP production for the journey through the female cervix , uterus , and uterine tubes .

During fertilization , the sperm provides three essential parts to the oocyte : (1) a signalling or activating factor, which causes the metabolically dormant oocyte to activate; (2) the haploid paternal genome ; (3) the centriole, which is responsible for forming the centrosome and microtubule system. [12]

The spermatozoa of animals are produced through spermatogenesis inside the male gonads ( testicles ) via meiotic division. The initial spermatozoon process takes around 70 days to complete. The process starts with the production of spermatogonia from germ cell precursors. These divide and differentiate into spermatocytes , which undergo meiosis to form spermatids . In the spermatid stage, the sperm develops the familiar tail. The next stage where it becomes fully mature takes around 60 days when it is called a spermatozoan . [13] Sperm cells are carried out of the male body in a fluid known as semen . Human sperm cells can survive within the female reproductive tract for more than 5 days post coitus. [14] Semen is produced in the seminal vesicles , prostate gland and urethral glands .

In 2016, scientists at Nanjing Medical University claimed they had produced cells resembling mouse spermatids from mouse embryonic stem cells artificially. They injected these spermatids into mouse eggs and produced pups. [15]

Sperm quantity and quality are the main parameters in semen quality, which is a measure of the ability of semen to accomplish fertilization . Thus, in humans, it is a measure of fertility in a man . The genetic quality of sperm, as well as its volume and motility, all typically decrease with age . [16]

DNA damages present in sperm cells in the period after meiosis but before fertilization may be repaired in the fertilized egg, but if not repaired, can have serious deleterious effects on fertility and the developing embryo. Human sperm cells are particularly vulnerable to free radical attack and the generation of oxidative DNA damage, [17] such as that from 8-Oxo-2'-deoxyguanosine .

The postmeiotic phase of mouse spermatogenesis is very sensitive to environmental genotoxic agents, because as male germ cells form mature sperm they progressively lose the ability to repair DNA damage. [18] Irradiation of male mice during late spermatogenesis can induce damage that persists for at least 7 days in the fertilizing sperm cells, and disruption of maternal DNA double-strand break repair pathways increases sperm cell-derived chromosomal aberrations. [19] Treatment of male mice with melphalan , a bifunctional alkylating agent frequently employed in chemotherapy, induces DNA lesions during meiosis that may persist in an unrepaired state as germ cells progress through DNA repair-competent phases of spermatogenic development. [20] Such unrepaired DNA damages in sperm cells, after fertilization, can lead to offspring with various abnormalities.

Related to sperm quality is sperm size, at least in some animals. For instance, the sperm of some species of fruit fly ( Drosophila ) are up to 5.8 cm long—about 20 times as long as the fly itself. Longer sperm cells are better than their shorter counterparts at displacing competitors from the female's seminal receptacle. The benefit to females is that only healthy males carry "good" genes that can produce long sperm in sufficient quantities to outcompete their competitors. [21] [22]

Some sperm banks hold up to 170 litres (37 imp gal; 45 US gal) of sperm. [23]

In addition to ejaculation , it is possible to extract sperm through testicular sperm extraction .

On the global market, Denmark has a well-developed system of human sperm export. This success mainly comes from the reputation of Danish sperm donors for being of high quality [24] and, in contrast with the law in the other Nordic countries, gives donors the choice of being either anonymous or non-anonymous to the receiving couple. [24] Furthermore, Nordic sperm donors tend to be tall and highly educated [25] and have altruistic motives for their donations, [25] partly due to the relatively low monetary compensation in Nordic countries. More than 50 countries worldwide are importers of Danish sperm, including Paraguay , Canada , Kenya , and Hong Kong . [24] However, the Food and Drug Administration (FDA) of the US has banned import of any sperm, motivated by a risk of transmission of Creutzfeldt–Jakob disease ,
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