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Duvernoy's Gland
The Duvernoy's gland is a gland found in some groups of '' colubrid'' snakes. It is distinguished from the venom gland and is not found in '' viperids'' or ''elapids''. It was named for French zoologist Georges Louis Duvernoy who first described the gland in 1832. The Duvernoy's gland is positioned posterior to the eye, encased in a thin cover of connective tissue, and consists mostly of serous cells. A single, short duct extends anteromedially from the lumen of the gland to the base of the posterior fangs. Function The function of the Duvernoy's gland has been the source of much study and speculation, and debate is still ongoing. It is widely recognized that the Duvernoy's gland is the homologue of venom glands in vipers and elapids. However, the two types of glands are also “anatomically and functionally distinct,” leading experts such as Dr. Kenneth Kardong to maintain the distinction between the Duvernoy's gland and venom glands. Other scientists such as Dr. Bryan Fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DG Arrow
DG may refer to: Arts and entertainment * Death Grips, an American experimental hip hop group * DG (character), in the science fiction series ''Tin Man'' * Dial Global, a radio network * Dragon Gate, a Japanese professional wrestling promotion * Drain Gang, a Swedish rap group Business and organizations * Data General, a minicomputer manufacturer * DG Flugzeugbau, a German airplane manufacturer * Desnoes & Geddes, DG, D&G, a Jamaican brand of soft drinks * Deutsche Grammophon, a classical music record label * Dial Global, a radio network * Dolce & Gabbana, an Italian luxury fashion design * Dollar General, an American variety store (NYSE ticker DG) * Cebgo, formerly South East Asian Airlines, SEAir, Tigerair Philippines; IATA code *Delta Gamma, a women's fraternity Places * DG postcode area, the Dumfries and Galloway postcode area in Scotland * Danilovgrad, a municipality in Montenegro, abbreviated DG on car plates * German-speaking Community of Belgium (german: Deutschspra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colubrid
Colubridae (, commonly known as colubrids , from la, coluber, 'snake') is a family of snakes. With 249 genera, it is the largest snake family. The earliest species of the family date back to the Oligocene epoch. Colubrid snakes are found on every continent except Antarctica. Description While most colubrids are not venomous (or have venom that is not known to be harmful to humans) and are mostly harmless, a few groups, such as genus '' Boiga'', can produce medically significant injuries. In addition, the boomslang, the twig snakes, and the Asian genus ''Rhabdophis'' have caused human fatalities. Some colubrids are described as opisthoglyphous (often called "rear-fanged"), meaning they have elongated, grooved teeth located in the back of their upper jaws. It is likely that opisthoglyphous dentition evolved many times in the history of snakes and is an evolutionary precursor to the fangs of vipers and elapids, which are located in the front of the mouth. Classification In th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snake
Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads (cranial kinesis). To accommodate their narrow bodies, snakes' paired organs (such as kidneys) appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca. Lizards have evolved elongate bodies without limbs or with greatly reduced limbs about twenty-five times independently via convergent evolution, leading to many lineages of legless lizards. These resemble snakes, but several common groups of legless lizards have eyelids and external ears, which snakes lack, although this rule is not universal (see Amphisbaen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viperid
The Viperidae (vipers) are a family of snakes found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, and various other isolated islands. They are venomous and have long (relative to non-vipers), hinged fangs that permit deep penetration and injection of their venom. Four subfamilies are currently recognized. They are also known as viperids. The name "viper" is derived from the Latin word ''vipera'', -''ae'', also meaning viper, possibly from ''vivus'' ("living") and ''parere'' ("to beget"), referring to the trait viviparity (giving live birth) common in vipers like most of the species of Boidae. Description All viperids have a pair of relatively long solenoglyphous (hollow) fangs that are used to inject venom from glands located towards the rear of the upper jaws, just behind the eyes. Each of the two fangs is at the front of the mouth on a short maxillary bone that can rotate back and forth. When not in use, the fangs fold back against the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elapid
Elapidae (, commonly known as elapids ; grc, ἔλλοψ ''éllops'' "sea-fish") is a family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous, with the exception of the genus Emydocephalus. Many members of this family exhibit a threat display of rearing upwards while spreading out a neck flap. Elapids are endemic to tropical and subtropical regions around the world, with terrestrial forms in Asia, Australia, Africa, and the Americas and marine forms in the Pacific and Indian Oceans. Members of the family have a wide range of sizes, from the white-lipped snake to the king cobra. Most species have neurotoxic venom which is channeled by their hollow fangs, and some may contain other toxic components in various proportions. The family includes 55 genera with some 360 species and over 170 subspecies. Description Terrestrial elapids look similar to the Colubridae; almost all have long, slender bodies with smooth scal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area extends from the Rhine to the Atlantic Ocean and from the Mediterranean Sea to the English Channel and the North Sea; overseas territories include French Guiana in South America, Saint Pierre and Miquelon in the North Atlantic, the French West Indies, and many islands in Oceania and the Indian Ocean. Due to its several coastal territories, France has the largest exclusive economic zone in the world. France borders Belgium, Luxembourg, Germany, Switzerland, Monaco, Italy, Andorra, and Spain in continental Europe, as well as the Netherlands, Suriname, and Brazil in the Americas via its overseas territories in French Guiana and Saint Martin. Its eighteen integral regions (five of which are overseas) span a combined area of and contain clos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zoologist
Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. The term is derived from Ancient Greek , ('animal'), and , ('knowledge', 'study'). Although humans have always been interested in the natural history of the animals they saw around them, and made use of this knowledge to domesticate certain species, the formal study of zoology can be said to have originated with Aristotle. He viewed animals as living organisms, studied their structure and development, and considered their adaptations to their surroundings and the function of their parts. The Greek physician Galen studied human anatomy and was one of the greatest surgeons of the ancient world, but after the fall of the Western Roman Empire an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Georges Louis Duvernoy
Georges Louis Duvernoy (6 August 1777, Montbéliard, Doubs – 1 March 1855) was a French zoologist. He assisted Georges Cuvier in writing ''Leçons d'anatomie comparée''. He was elected a member of the French Academy of Sciences in 1847 and a foreign member of the Royal Swedish Academy of Sciences in 1851. He studied in Stuttgart, Strasbourg, and Paris, and in 1802 was asked by Cuvier (a distant cousin) to help edit his masterpiece on comparative anatomy. From notes and counsel from Cuvier, Duvernoy prepared the last three volumes of ''Leçons d'anatomie comparée'', writings that involved respiration, circulation, digestive organs, et al. In 1805 he returned to Montbéliard, where he worked as a practitioner of medicine. In 1827 he was elected professor to the Faculty of Sciences at Strasbourg, and during the next ten years published a number of treatises on anatomical subjects. After the death of Cuvier in 1832, he worked at arranging his papers for publication. In 183 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serous Cell
The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands (parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. Salivary glands can be classified as serous, mucous, or seromucous (mixed). In serous secretions, the main type of protein secreted is alpha-amylase, an enzyme that breaks down starch into maltose and glucose, whereas in mucous secretions, the main protein secreted is mucin, which acts as a lubricant. In humans, 1200 to 1500 ml of saliva are produced every day. The secretion of saliva (salivation) is mediated by parasympathetic stimulation; acetylcholine is the active neurotransmitter and binds to muscarinic receptors in the glands, leading to increased salivation. The fourth pair of salivary glands, the tubarial glands discovered in 2020, are named for their location, being positioned in front and over the torus tubarius. However, this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Venom
Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a stinger, in a process called envenomation. Venom is often distinguished from poison, which is a toxin that is passively delivered by being ingested, inhaled, or absorbed through the skin, and toxungen, which is actively transferred to the external surface of another animal via a physical delivery mechanism. Venom has evolved in terrestrial and marine environments and in a wide variety of animals: both predators and prey, and both vertebrates and invertebrates. Venoms kill through the action of at least four major classes of toxin, namely necrotoxins and cytotoxins, which kill cells; neurotoxins, which affect nervous systems; myotoxins, which damage muscles; and haemotoxins, which disrupt blood clotting. Venomous animals cause tens of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell ( cytotoxicity) or an organ such as the liver (hepatotoxicity). By extension, the word may be metaphorically used to describe toxic effects on larger and more complex groups, such as the family unit or society at large. Sometimes the word is more or less synonymous with poisoning in everyday usage. A central concept of toxicology is that the effects of a toxicant are dose-dependent; even water can lead to water intoxication when taken in too high a dose, whereas for even a very toxic substance such as snake venom there is a dose below which there is no detectable toxic effect. Toxicity is species-specific, making cross-species analysis problematic. Newer paradigms and metrics are evolving to byp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glands
In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure Development Every gland is formed by an ingrowth from an epithelial surface. This ingrowth may in the beginning possess a tubular structure, but in other instances glands may start as a solid column of cells which subsequently becomes tubulated. As growth proceeds, the column of cells may split or give off offshoots, in which case a compound gland is formed. In many glands, the number of branches is limited, in others (salivary, pancreas) a very large structure is finally formed by repeated growth and sub-division. As a rule, the branches do not unite with one another, but in one instance, the liver, this does occur when a reticulated compound gland is produced. In compound glands the more typical or secretory epithelium is found forming ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
