All articles starting with M
36,687 articles
Mesocardia
Mesocardia, or midline heart, is a rare congenital malposition in which the heart sits centrally in the thorax with a midline apex; usually normal atrial situs, possibly inverted ventricles, about 0.2% of congenital anomalies.
Mesocosm
A mesocosm is a controlled experimental system at an intermediate scale, such as a large tank or in-water enclosure, that lets ecologists study ecosystem processes under realistic conditions between laboratory microcosms and the open field.
Mesocricetus
Mesocricetus, also known as golden hamsters, is a genus of medium-sized hamsters established in 1898; its most famous member is the common pet and research animal.
Mesocyclone
A mesocyclone is a storm-scale region of cyclonic rotation, typically 2 to 6 miles in diameter, found in the right rear flank of a supercell thunderstorm and defined by a Doppler radar rotation signature.
Mesocyclops
Mesocyclops is a genus of small predatory copepods established by G. O. Sars in 1914, used as biological control agents against dengue-carrying mosquito larvae, most extensively in Vietnam.
Mesoderm
Mesoderm: the middle embryonic germ layer, between ectoderm and endoderm, formed at gastrulation. Gives rise to muscle, bone, heart, blood, kidneys, mesenchyme; induced by Nodal, FGF, Wnt, BMP signaling; discovered by Pander, named by Huxley.
Mesodermal cell
A mesodermal cell, also called a mesoderm cell or mesoblast, is a cell of the middle germ layer of the embryo, the mesoderm, which forms during gastrulation.
Mesoeconomics
Mesoeconomics is a proposed intermediate level of economic analysis between microeconomics and macroeconomics, variously defined as the study of sectors, large corporations, or production networks, and remains outside mainstream economics.
Mesoglea
Mesoglea: jelly-like extracellular matrix between ectoderm and endoderm in cnidarians and ctenophores; about 98% water in jellyfish, collagenous, supports transport, nerve nets, morphogenesis, and regeneration.
Mesohippus
Mesohippus, the "middle horse", an extinct three-toed North American horse genus of 37-32 million years ago, intermediate between Eocene Hyracotherium-like horses and later horses, with molarized premolars and pad-footed tridactyl limbs.
Mesojassoides
Mesojassoides is an extinct monotypic leafhopper genus (Cicadellidae) from the Maastrichtian Fox Hills Sandstone of Colorado, 70.6–66 Ma; its single species M. gigantea Oman, 1937 is known from a 12 mm holotype fore wing.
Mesolimbic pathway
Mesolimbic pathway: dopamine projection from the ventral tegmental area to limbic structures, chiefly the nucleus accumbens. Central to reward, incentive salience ('wanting'), prediction error learning, addiction, depression, and schizophrenia research.
Mesolithic
The Mesolithic, or Middle Stone Age, is the archaeological period of Europe's last hunter-gatherer-fisher societies, defined by hunting, fishing, and gathering, with the dog the only domesticated animal.
Mesomelia-synostoses syndrome
Mesomelia-synostoses syndrome (Verloes-David-Pfeiffer syndrome, 8q13 microdeletion syndrome) is a rare autosomal dominant skeletal dysplasia with mesomelic limb shortening, acral synostoses, facial features, and palatal anomalies, caused by SULF1/SLCO5A1 deletions.
Mesomelic dysplasia, Kantaputra type
Mesomelic dysplasia, Kantaputra type (MDK, Thai type) is a rare autosomal dominant skeletal dysplasia with mesomelic limb shortening, fibulo-calcaneal synostosis, and HOXD-cluster duplications at 2q31.1-q31.2.
Mesomelic dysplasia, Nievergelt type
Mesomelic dysplasia, Nievergelt type (Nievergelt syndrome, ORPHA:2633) is an extremely rare bone dysplasia with severe mesomelic limb shortening, triangular or rhomboid tibiae and fibulae, synostoses, and skin dimples; onset antenatal or neonatal.
Mesomelic dysplasia, Savarirayan type
Mesomelic dysplasia, Savarirayan type (triangular tibia-fibular aplasia syndrome, OMIM 605274) is a rare skeletal dysplasia with hypoplastic triangular tibiae and absent fibulae, caused by de novo 6p22.3 microdeletions affecting ID4 regulation.
Mesomeric effect
The mesomeric effect, also called the resonance effect, is the effect of a substituent on reaction rates and equilibria through p- or π-orbital overlap and charge delocalization, symbol M.
Meson
A meson is a hadron made of one quark and one antiquark bound by the strong interaction, unlike baryons, which contain three quarks; all known mesons are unstable.
Mesonephric duct
Mesonephric duct (Wolffian duct): paired embryonic ducts from intermediate mesoderm that form the ureteric bud and, under testosterone, the epididymis, vas deferens, and seminal vesicles; they atrophy in females, leaving Gartner duct remnants.
Mesonephros
Mesonephros: the second embryonic kidney of vertebrates (after pronephros, before metanephros), from intermediate mesoderm; functional weeks 4-8 in humans, adult kidney in fish and amphibians, source of Wolffian duct male reproductive derivatives.
Mesophyllum
Mesophyllum is a genus of calcified crustose red algae in the family Hapalidiaceae, established by Marie Lemoine in 1928 and found from temperate Northern Hemisphere waters to the Mediterranean.
Mesoplodon
Mesoplodon, mesoplodont beaked whales, the most speciose cetacean genus with 15-16 species of 3.9-6.2 m deep-diving suction-feeding whales; males bear a single diagnostic tusk pair used in combat.
Mesoplodon densirostris
Mesoplodon densirostris, Blainville's beaked whale or dense-beaked whale, a deep-diving ziphiid of tropical to warm temperate seas worldwide, the widest-ranging Mesoplodon, with arched-jawed tusked males, 833 m mean foraging dives, and sonar sensitivity.
Mesoporous silica nanoparticle
A mesoporous silica nanoparticle (MSN) is a porous silica particle with 2 to 50 nm pores, developed to load and release drugs in a controlled way.
Mesopotamia
Mesopotamia, the land between the Tigris and Euphrates in modern Iraq and northeast Syria, saw the first cities, cuneiform writing, codified law, and the first empire under Sargon of Akkad.
Mesopotamia Argentina
Mesopotamia Argentina (Argentine Mesopotamia, Región Mesopotámica) is the northeastern Argentine region between the Paraná and Uruguay rivers, comprising Misiones, Corrientes, and Entre Ríos provinces, about 196,000 km², named by Martín de Moussy in 1860.
Mesopotamian Arabic
Mesopotamian Arabic (Iraqi Arabic, عراقي) is the Arabic dialect group of Iraq, northeast Syria, southeast Turkey, and Khuzestan, with about 30 million speakers, split into gilit and qeltu varieties and marked by q-to-g, k-to-ch shifts and Aramaic, Persian, and Turkish loanwords.
Mesopotamian campaign
Mesopotamian campaign (1914-1918): British and Indian forces fought the Ottoman Empire in Mesopotamia, now Iraq, taking Basra in 1914, suffering the siege and surrender at Kut in 1916, capturing Baghdad under Maude in March 1917, and taking Mosul after the Mudros armistice.
Mesopotamian flood event
The Mesopotamian flood event, or Shuruppak flood, is an archaeological flood deposit at Shuruppak (Fara), Iraq, dated to about 2900 BC and traditionally linked to the Mesopotamian flood legend.