Teratology is the study of abnormalities of physiological development in organisms during their life span. It is a sub-discipline in medical genetics which focuses on the classification of congenital abnormalities in dysmorphology caused by teratogens and also in pharmacology and toxicology. Teratogens are substances that may cause non-heritable birth defects via a toxic effect on an embryo or fetus. Defects include malformations, disruptions, deformations, and dysplasia that may cause stunted growth, delayed mental development, or other congenital disorders that lack structural malformations. These defects can be recognized prior to or at birth as well as later during early childhood. The related term developmental toxicity includes all manifestations of abnormal development that are caused by environmental insult. The extent to which teratogens will impact an embryo is dependent on several factors, such as how long the embryo has been exposed, the stage of development the embryo was in when exposed (gestational timing), the genetic makeup of the embryo, and the transfer rate of the teratogen. The dose of the teratogen, the route of exposure to the teratogen, and the chemical nature of the teratogenic agent also contribute to the level of teratogenicity.
👉 Teratology in the context of Linear no-threshold model
The linear no-threshold model (LNT) is a dose-response model used in radiation protection to estimate stochastic health effects such as radiation-induced cancer, genetic mutations and teratogenic effects on the human body due to exposure to ionizing radiation. The model assumes a linear relationship between dose and health effects, even for very low doses where biological effects are more difficult to observe. The LNT model implies that all exposure to ionizing radiation is harmful, regardless of how low the dose is, and that the effect is cumulative over a lifetime.
The LNT model is commonly used by regulatory bodies as a basis for formulating public health policies that set regulatory dose limits to protect against the effects of radiation. The validity of the LNT model, however, is disputed, and other models exist: the threshold model, which assumes that very small exposures are harmless, the radiation hormesis model, which says that radiation at very small doses can be beneficial, and the supra-linear model. It has been argued that the LNT model may have created an irrational fear of radiation.
Teratology in the context of Embryology
Embryology (from Greek ἔμβρυον, embryon, "the unborn, embryo"; and -λογία, -logia) is the branch of zoology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses. Embryology includes teratology, the study of congenital disorders that occur before birth.
Early embryology was proposed by Marcello Malpighi, and known as preformationism, the theory that organisms develop from pre-existing miniature versions of themselves. Aristotle proposed the now-accepted theory of epigenesis, the idea that organisms develop from seed or egg in a sequence of steps. Modern embryology developed from the work of Karl Ernst von Baer, though accurate observations had been made in Italy by anatomists such as Aldrovandi and Leonardo da Vinci in the Renaissance.
View the full Wikipedia page for EmbryologyTeratology in the context of Neurofibromatosis
Neurofibromatosis (NF) refers to a group of three distinct genetic conditions in which tumors grow in the nervous system. The tumors are non-cancerous (benign) and often involve the skin or surrounding bone. Although symptoms are often mild, each condition presents differently. Neurofibromatosis type I (NF1) is typically characterized by café au lait spots (light-brown flat patches of skin), neurofibromas (small bumps in or under the skin), scoliosis (side-way curvature of the back), and headaches. Neurofibromatosis type II (NF2), on the other hand, may present with early-onset hearing loss, cataracts, tinnitus, difficulty walking or maintaining balance, and muscle atrophy. The third type is called schwannomatosis and often presents in early adulthood with widespread pain, numbness, or tingling due to nerve compression.
The cause is a genetic mutation in certain oncogenes. These can be inherited, or in about half of cases spontaneously occur during early development. Different mutations result in the three types of NF. Neurofibromatosis arise from the supporting cells of the nervous system rather than the neurons themselves. In NF1, the tumors are neurofibromas (tumors of the peripheral nerves), while in NF2 and schwannomatosis tumors of Schwann cells are more common. Diagnosis is typically based on symptoms, examination, medical imaging, and biopsy. Genetic testing may rarely be done to support the diagnosis.
View the full Wikipedia page for NeurofibromatosisTeratology in the context of Embryological
Embryology (from Greek ἔμβρυον, embryon, 'the unborn, embryo'; and -λογία, -logia) is the branch of zoology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses. Embryology includes teratology, the study of congenital disorders that occur before birth.
Early embryology was proposed by Marcello Malpighi, and known as preformationism, the theory that organisms develop from pre-existing miniature versions of themselves. Aristotle proposed the now-accepted theory of epigenesis, the idea that organisms develop from seed or egg in a sequence of steps. Modern embryology developed from the work of Karl Ernst von Baer, though accurate observations had been made in Italy by anatomists such as Aldrovandi and Leonardo da Vinci in the Renaissance.
View the full Wikipedia page for EmbryologicalTeratology in the context of Zebrafish
The zebrafish (Danio rerio) is a species of freshwater ray-finned fish belonging to the family Danionidae of the order Cypriniformes. Native to South Asia, it is a popular aquarium fish, frequently sold under the trade name zebra danio (and thus often called a "tropical fish" although it is both tropical and subtropical).
The zebrafish is an important and widely used vertebrate model organism in scientific research, particularly developmental biology, but also gene function, oncology, teratology, and drug development, in particular pre-clinical development, due to its scalability from high numbers of offspring and ease of drug delivery through water into the gills. It is also notable for its regenerative abilities, and has been modified by researchers to produce many transgenic strains.
View the full Wikipedia page for Zebrafish