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Sperm Sorting
Sperm sorting is a means of choosing what type of sperm cell is to fertilize the egg cell. Several conventional techniques of centrifugation or swim-up. Newly applied methods such as flow cytometry expand the possibilities of sperm sorting and new techniques of sperm sorting are being developed. It can be used to sort out sperm that are most healthy, as well as for determination of more specific traits, such as sex selection in which spermatozoa are separated into X- (female) and Y- (male) chromosome bearing populations based on their difference in DNA content. The resultant 'sex-sorted' spermatozoa are then able to be used in conjunction with other assisted reproductive technologies such as artificial insemination or in-vitro fertilization (IVF) to produce offspring of the desired sex - in farming animals but also in human medical practice. Methods Conventional techniques Several methods have been used to sort sperm before the advent of flow cytometry. Density gradien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sperm Cell
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. Flowering plants contain non-motile sperm inside pollen, while some more basal plants like ferns and some gymnosperms have motile sperm. Sperm cells form during the process known as spermatogenesis, which in amniotes (reptiles and mammals) takes place in the seminiferous tubules of the testes. 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, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annexin V
Annexin A5 (or annexin V) is a cellular protein in the annexin group. In flow cytometry, annexin V is commonly used to detect apoptotic cells by its ability to bind to phosphatidylserine, a marker of apoptosis when it is on the outer leaflet of the plasma membrane. The function of the protein is unknown; however, annexin A5 has been proposed to play a role in the inhibition of blood coagulation by competing for phosphatidylserine binding sites with prothrombin and also to inhibit the activity of phospholipase A1. These properties have been found by in vitro experiments. Pathology Antibodies directed against annexin A5 are found in patients with a disease called the antiphospholipid syndrome (APS), a thrombophilic disease associated with autoantibodies against phospholipid compounds. Annexin A5 forms a shield around negatively charged phospholipid molecules. The formation of an annexin A5 shield blocks the entry of phospholipids into coagulation (clotting) reactions. In the ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Assisted Reproductive Technology
Assisted reproductive technology (ART) includes medical procedures used primarily to address infertility. This subject involves procedures such as in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), cryopreservation of gametes or embryos, and/or the use of fertility medication. When used to address infertility, ART may also be referred to as fertility treatment. ART mainly belongs to the field of reproductive endocrinology and infertility. Some forms of ART may be used with regard to fertile couples for genetic purpose (see preimplantation genetic diagnosis). ART may also be used in surrogacy arrangements, although not all surrogacy arrangements involve ART. The existence of sterility will not always require ART to be the first option to consider, as there are occasions when its cause is a mild disorder that can be solved with more conventional treatments or with behaviors based on promoting health and reproductive habits. Procedures General With ART, the pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congenital Disorder
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth defects are divided into two main types: structural disorders in which problems are seen with the shape of a body part and functional disorders in which problems exist with how a body part works. Functional disorders include metabolic and degenerative disorders. Some birth defects include both structural and functional disorders. Birth defects may result from genetic or chromosomal disorders, exposure to certain medications or chemicals, or certain infections during pregnancy. Risk factors include folate deficiency, drinking alcohol or smoking during pregnancy, poorly controlled diabetes, and a mother over the age of 35 years old. Many are believed to involve multiple factors. Birth defects may be vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Viability
Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery with only a few monks or nuns * Prison cell, a room used to hold people in prisons Groups of people * Cell, a group of people in a cell group, a form of Christian church organization * Cell, a unit of a clandestine cell system, a penetration-resistant form of a secret or outlawed organization * Cellular organizational structure, such as in business management Science, mathematics, and technology Computing and telecommunications * Cell (EDA), a term used in an electronic circuit design schematics * Cell (microprocessor), a microprocessor architecture developed by Sony, Toshiba, and IBM * Memory cell (computing), the basic unit of (volatile or non-volatile) computer memory * Cell, a unit in a database table or spreadsheet, formed by the i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactive Oxygen Species
In chemistry, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (). Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen. The reduction of molecular oxygen () produces superoxide (), which is the precursor to most other reactive oxygen species: :O2 + e^- -> \ ^\bullet O2- Dismutation of superoxide produces hydrogen peroxide (): :2 H+ + \ ^\bullet O2^- + \ ^\bullet O2^- -> H2O2 + O2 Hydrogen peroxide in turn may be partially reduced, thus forming hydroxide ions and hydroxyl radicals (), or fully reduced to water: :H2O2 + e^- -> HO^- + \ ^\bullet OH :2 H+ + 2 e- + H2O2 -> 2 H2O In a biological context, ROS are byproducts of the normal metabolism of oxygen. ROS have roles in cell signaling and homeostasis. ROS are intrinsic to cellular functioning, and are present at low and stationary levels in normal cells. In plants, ROS are involved in metabolic processes related to photoprotection and toleran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sperm Motility
Sperm motility describes the ability of sperm to move properly through the female reproductive tract (internal fertilization) or through water (external fertilization) to reach the egg. Sperm motility can also be thought of as the ''quality'', which is a factor in successful conception; sperm that do not "swim" properly will not reach the egg in order to fertilize it. Sperm motility in mammals also facilitates the passage of the sperm through the cumulus oophorus (a layer of cells) and the zona pellucida (a layer of extracellular matrix), which surround the mammalian oocyte. In the wood mouse ''Apodemus sylvaticus'', sperms aggregate in 'trains' that are better able to fertilize eggs because they are more capable of navigating the viscous environment of the female reproductive tract. The trains move in a sinusoidal motion. Sperm motility is also affected by certain factors released by eggs. Sperm movement is activated by changes in intracellular ion concentration. The changes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with selective breeding, artificial selection, which in his view is intentional, whereas natural selection is not. Genetic diversity, Variation exists within all populations of organisms. This occurs partly because random mutations arise in the genome of an individual organism, and their offspring can inherit such mutations. Throughout the lives of the individuals, their genomes interact with their environments to cause variations in traits. The environment of a genome includes the molecular biology in the Cell (biology), cell, other cells, other individuals, populations, species, as well as the abiotic environment. Because individuals with certain variants of the trait tend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Z Method
Z (or z) is the 26th and last letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its usual names in English are ''zed'' () and ''zee'' (), with an occasional archaic variant ''izzard'' ()."Z", ''Oxford English Dictionary,'' 2nd edition (1989); ''Merriam-Webster's Third New International Dictionary of the English Language, Unabridged'' (1993); "zee", ''op. cit''. Name and pronunciation In most English-speaking countries, including Australia, Canada, India, Ireland, New Zealand and the United Kingdom, the letter's name is ''zed'' , reflecting its derivation from the Greek ''zeta'' (this dates to Latin, which borrowed Y and Z from Greek), but in American English its name is ''zee'' , analogous to the names for B, C, D, etc., and deriving from a late 17th-century English dialectal form. Another English dialectal form is ''izzard'' . This dates from the mid-18th century and probably derives fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrophoresis
Electrophoresis, from Ancient Greek ἤλεκτρον (ḗlektron, "amber") and φόρησις (phórēsis, "the act of bearing"), is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric field. Electrophoresis of positively charged particles (cations) is sometimes called cataphoresis, while electrophoresis of negatively charged particles (anions) is sometimes called anaphoresis. The electrokinetic phenomenon of electrophoresis was observed for the first time in 1807 by Russian professors Peter Ivanovich Strakhov and Ferdinand Frederic Reuss at Moscow University, who noticed that the application of a constant electric field caused clay particles dispersed in water to migrate. It is ultimately caused by the presence of a charged interface between the particle surface and the surrounding fluid. It is the basis for analytical techniques used in chemistry for separating molecules by size, charge, or binding affinity. Electropho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intracytoplasmic Sperm Injection
Intracytoplasmic sperm injection (ICSI ) is an in vitro fertilization (IVF) procedure in which a single sperm cell is injected directly into the cytoplasm of an egg. This technique is used in order to prepare the gametes for the obtention of embryos that may be transferred to a maternal uterus. With this method, the acrosome reaction is skipped. There are several differences between classic IVF and ICSI. However, the steps to be followed before and after insemination are the same. In terms of insemination, ICSI needs only one sperm cell per oocyte, while IVF needs 50,000–100,000. This is because the acrosome reaction has to take place and thousands of sperm cells have to be involved in IVF. Once fertilized, the egg is transformed into a pre-embryo and it has to be transferred to the uterus to continue its development. The first human pregnancy generated by ICSI was carried out in 1991 by Gianpiero Palermo and his team. Round spermatid injection (ROSI) Round spermatid inject ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
