embryo sacThe mature female gametophyte in angiosperms. Generally a seven-celled structure - two synergids, one egg cell, three antipodal cells (each with a single…
embryo sexingThe determination of the sex of an embryo prior to birth. Typically achieved by the polymerase chain reaction -mediated amplification of DNA extracted…
embryo splittingThe splitting of young embryos into several sections, each of which develops into an animal. A form of animal cloning, i.e.
embryo storageCryogenic preservation of animal embryos, allowing inembryonation or other manipulations long after embryo formation.
embryo technologyGeneric name for any modification of mammalian embryos. It encompasses embryo cloning, embryo splitting, embryo storage, and in vitro fertilization.
embryo transfer(Abbreviation: ET). See: embryo multiplication and transfer, multiple ovulation and embryo transfer.
embryogenesis1. (General) Development of an embryo. 2. (In plants) In vitro formation of plants from plant tissues, through a pathway closely resembling normal…
embryoidPlant biotechnology term no longer commonly used. An embryo-like body developing in vitro, forming a complete, self-contained plantlet with no vascular…
Embryoid bodies (EBs)Spheroid colonies seen in culture produced by the growth of embryonic stem cells in suspension.
Embryonic diskA group of cells derived from the inner cell mass of the blastocyst, which later develops into an embryo.
Embryonic germ (EG) cellsCells found in a specific part of the embryo/fetus called the gonadal ridge that normally develop into mature gametes.
Embryonic germline cellsEmbryonic germline cells, also called EG cells, are pluripotent stem cells derived from the primitive germline cells (those cells that give rise to eggs…
Embryonic stem (ES) cellsCell lines derived from early embryos that have the potential to differentiate into all types of somatic cells as well as to form germ line cells, and…
Embryonic stem cellAlso called ES cells, embryonic stem cells are cells derived from the inner cell mass of developing blastocysts.
Embryonic stem cell lineEmbryonic stem cells, which have been cultured under in vitro conditions that allow proliferation without differentiation for months to years.
Embryonic stem cells(Abbreviation: ES cells). Cells of the early embryo that can give rise to all differentiated cells, including germ line cells.
EmbryotoxicityAdverse effects on the embryo due to a substance that enters the maternal system and crosses the placental barrier.
EmergencyA serious situation that happens unexpectedly and demands immediate action.
Emergency Action PlanA predetermined plan of action to be taken to reduce the potential for property damage and loss of lives in an area affected by a dam break or excessive…
Emergency action plan (EAP)Reclamation procedures for dam operating personnel to follow during emergency situations or unusual occurrences at a given dam to reduce potential for…
Emergency broadcast systemA federally established network of commercial radio stations that voluntarily provide official emergency instructions or directions to the public during…
Emergency classification levelsA phased system in which dam operating organizations classify dam safety emergency incidents into response levels according to how severe they are at the…
Emergency evacuation zonesGeographical areas delineated in inundation areas downstream from a dam (hazard generator) that define the potential area of impact and allow prioritizing…
Emergency ExerciseAn activity designed to promote emergency preparedness; evaluate emergency operations, policies, plans, procedures, and facilities; train personnel in…
Emergency GateA standby or auxiliary gate used when the normal means of water control is not available.
Emergency managementThe system by which mitigation, preparedness, response, and recovery activities are undertaken to save lives and protect property from all hazards.
Emergency management agencyAny State or local agency responsible for emergency operations, planning, mitigation, preparedness, response, and recovery for all hazards.
Emergency operations centerThe location of facility where responsible officials gather during an emergency to direct and coordinate emergency operations, to communicate with other…
Emergency operations plan (State and local)A plan, usually developed in accord with guidance contained in the Guide for the Development of State and Local Emergency Operations Plans, Civil…
Emergency program managerThe individual responsible on a day-to-day basis for a jurisdiction's effort to develop a capability for coordinated response to and recovery from the…
Emergency reserve fundMoney reserved or required by contract to be reserved by an operating entity for use in emergency situations involving facilities under the entity's…
Emergency ServicesEvaluation of an emergency medical condition and treatment to keep the condition from getting worse.
Emergency SpillwayA spillway which provides for additional safety should emergencies not contemplated by normal design assumptions be encountered, i.e.
EmergentAquatic plants having some or most of the leaf area extending out of the water.
Emergent wetlandsThe Emergent wetland class is characterized by erect, rooted, herbaceous hydrophytes, excluding mosses and lichens.
Emerging Flux Region (EFR)In solar-terrestrial terms, an area on the sun where new magnetic flux is erupting.
Eminent DomainWhen a government takes private property for public use. The owner receives payment for its fair market value.
Emission Control TechnologiesEquipment used in diesel-powered vehicles to reduce exhaust emissions, such as particulate matter and nitrogen oxides.
Emission FactorA measure of the average amount of a specified pollutant or material emitted for a specific type of fuel or process.
Emission inventoryA list of air pollutants emitted into a community's, state's, nation's, or the Earth's atmosphere in amounts per some unit time (e.g.
Emission offsetA reduction in the air pollution emissions of existing sources to compensate for emissions from new sources.
emission wavelengthThe specific wavelength of light emitted by a fluorescent molecule, such as a labelled probe, upon absorption of light at the (higher) excitation…
Emission(s)A substance(s) or pollutant emitted as a result of a process.
EmissionsWaste substances released into the air or water.
Emissions coefficient/factorA unique value for scaling emissions to activity data in terms of a standard rate of emissions per unit of activity (e.g.
Emissions FactorA unique value for scaling emissions to activity data in terms of a standard rate of emissions per unit of activity (e.g.
EmissivityThe ratio of the radiant energy (heat) leaving (being emitted by) a surface to that of a black body at the same temperature and with the same area…
emittanceThe rate at which a black body radiates energy across all wavelengths.
End UseA classification system for U.S. exported and imported merchandise based on principal use rather than the physical characteristics of the merchandise.
end-labellingThe introduction of a readily-visualized tag at the end of a DNA or RNA molecule.
end-product inhibitionThe inhibition of an enzyme by a metabolite. Typically, the enzyme is the first enzyme in a biosynthetic pathway, and the metabolite the product of the…
EndangeredSpecies that are in danger of extinction. It also is a category that denotes protection under federal law (Endangered Species Act).
Endangered speciesA plant or animal species in immediate danger of extinction because its population number has reached a critical level, or its habitat has been…
Endangered species act (ESA)This act provides a framework for the protection of endangered and threatened species. See Endangered Species Act of 1973.
Endangered Species Act of 1973 (ESA)Requires consultation with the U.S. Fish and Wildlife Service and/or the National Marine Fisheries Service to determine whether endangered or threatened…
EndemicWhere disease occurs on a consistent basis.
endocrine glandAny gland in an animal that manufactures hormones and secretes them directly into the bloodstream to act at distant sites in the body, known as target…
endocytosisThe process by which materials enter a cell without passing through the cell membrane.
EndodermThe internal layer of cells of the gastrula, which develops into the alimentary canal (gut) and digestive glands of the adult.
endodermisThe layer of living cells, with various characteristically thickened walls and no intercellular spaces, which surrounds the of certain plants and occurs…
endoplasmic reticulum(Abbreviation: ER). A cytoplasmic net of membranes, adjacent to the nucleus, visible under the electron microscope. The sites of protein synthesis.
endopolyploidyThe net result of endomitoses. The somatic chromosome number has doubled (or more), forming a polyploid cell line.
endoproteaseAn enzyme that cleaves internal peptide bonds within a polypeptide molecule. Site of cleavage is usually specific to certain amino acid residues.
endoreduplicationChromosome reproduction during interphase. Four-chromatid chromosomes (diplochromosomes) are seen during this phase.
endospermThe nutritive tissue that develops in the seed of most angiosperms, containing varying proportions of carbohydrate (usually starch), protein and lipid.
endosperm mother cellOne of the seven cells of the mature plant embryo sac, containing the two polar nuclei and, which, following fertilization, gives rise to the primary…
Endothelialrelating to a flat layer of cells lining the heart, for example, or blood vessels.
EndothermicA heat absorbing reaction or a reaction that requires heat.
endotoxinA component of the cell wall of gram-negative bacteria that elicits, in mammals, an inflammatory response and fever.
Energetic ParticlesThe atoms and molecules of a gas are in constant motion, colliding rapidly and filling all available space.
Energize(d)To send electricity through a electricity transmission and distribution network; a conductor or power line that is carrying current.
EnergyThe capability of doing work; different forms of energy can be converted to other forms, but the total amount of energy remains the same.
Energy AuditA survey that shows how much energy you use in your house or apartment. It will help you find ways to use less energy.
Energy ChargeThat part of an electricity bill that is based on the amount of electrical energy consumed or supplied.
Energy conservationReduction or elimination of unnecessary energy use and waste. See energy-efficiency.
energy cropA crop grown specifically for its fuel value. These include food crops such as corn and sugar cane, and nonfood crops such as poplar trees and switchgrass.
Energy CropsCrops grown specifically for their fuel value. These include food crops such as corn and sugarcane, and nonfood crops such as poplar trees and switchgrass.