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Technical terms glossary

When discussing scientific research and the regulation surrounding it, it can be difficult to keep up with all the technical terms and acronyms. Our technical terms glossy is here to help you understand the jargon so you can learn more about the issues you’re passionate about.

Is there a term you’re still looking for a definition of? Get in touch with us!

An adverse outcome pathway (AOP) is a model that uses knowledge of biological pathways and systems to help identify the events required to produce a toxic effect when an organism is exposed to a substance. AOP Frameworks provide guidance for the development on non-animal approaches for assessing toxicity of chemicals and safe drug development.

Any harmful, unintended reaction that results from the administration of a drug or medicine.

This term is used to refer to non-animal models or a combination of tests and methods that replace the need for animal experiments, such as in vitro and in silico techniques. These may also be referred to as non-animal or replacement methods/approaches or NAMs (New approach methodologies). In regulatory safety testing, these non-animal approaches are sometimes described as New Generation Risk Assessment (NGRA).

Learn more about some of the alternatives to animal research currently being used by researchers.

Sometimes alternative is also used to describe an alternative animal model which is not regulated and therefore viewed to suffer less, such as an invertebrate This is sometimes referred to as ‘Partial Replacement’.

Substances which relieve pain (e.g. paracetamol) These should be given to animals in research, where possible, as a ‘refinement’ to reduce suffering.

A preference for animal research-based approaches over non-animal approaches. This can occur for many reasons including a lack of confidence in new methods when compared to many years of animal tests or data in a specific area of research or testing. This bias can be seen in the funding and publication systems when animal approaches are viewed more favourably.

Learn more about animal bias in scientific publishing.

Any procedure applied to a protected animal for a qualifying purpose, such as any scientific, research, testing, or educational purpose. Also referred to as a scientific or animal procedure.

Learn more about what’s meant by a ‘procedure’ in animal research.

The view that animals have the right to be free from human use and exploitation. This includes the right not to be used for breeding, food production, for use in research or kept as pets.

The legislation that regulates the use of protected animals in scientific research in the United Kingdom. ASPA regulates procedures that are carried out, breeding and supplying of protected animals, and the methods used to euthanise protected animals.

Learn more about the Animals (Scientific Procedures) Act 1986 (APSA).

Refers to the well-being of an animal. Under the Animal Welfare Act to ensure good welfare, animals in captivity or under human control are required to be free of:

  • hunger and thirst
  • discomfort
  • pain, injury or disease
  • Inability to express normal behaviour
  • fear and distress

Legislation passed in 2006 that places a duty of care on people to ensure they take reasonable steps in all circumstances to meet the welfare needs of animals under their care to the extent required by good practice. They must take positive steps to ensure they care for their animals properly and in particular must provide for the five welfare needs, which are:

  • Need for a suitable environment
  • Need for a suitable diet
  • Need to be able to exhibit normal behaviour patterns
  • Need to be housed with or apart from other animals
  • Need to be protected from pain, suffering, injury and disease

This does not apply to invertebrates(excepting octopus), embryonic animals, wild animals (unless protected) or research animals.

Learn more about legislation and regulation in the UK for animals used in scientific research.

Substances used to treat bacterial infections (e.g. penicillin).

Specialised proteins produced by white blood cells in response to the introduction of a ‘foreign’ substance (antigen) into the body. The antibodies have the ability to recognise specific antigens and to bind to them very tightly. This ability to bind to specific molecules makes them ideal locators for use in cell research, where they are used to latch onto, isolate and help identify, molecules of interest in and on cells. Antibodies have become one of the most important tools for studying protein function in cells. Many antibodies used in research have historically been, or still are, animal-derived.

The growth and maintenance of living cells outside the body. This requires the provision of favourable artificial conditions to encourage cells to grow, such as the right temperature, nutrients and pH levels. This varies for different types of cell. Cells used may be obtained directly from living tissue (primary cells) or existing cell lines. Cell culture is an example of an ‘in vitro’ system.

Learn more about in vitro methods as an alternative to animal research.

Thread like structures found within the nucleus of cells containing genetic information (DNA) in the form of genes. Different species have different numbers of chromosomes.

The signs or symptoms of an illness, disease or injury that a doctor, vet or scientist can see.

A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease.

Cloning is the process of producing large numbers of genetically identical cells from a single cell, as is often required in cell culture. All of the cells of a clone have the same genes and produce exactly the same antibody. Whole organisms can also be cloned.

A term used within a laboratory animal context to mean a commitment to animal welfare, care of staff, transparency, and scientific quality. Culture of care is about going beyond what is expected by law to ensure compassion and respect to both the animal used in research, and the staff using them.

Learn more about what a culture of care is.

A group of small protein molecules including interferon, interleukin and growth factors, that are produced by cells of the immune system during inflammation. Cytokines are involved in signalling between cells, causing effects both locally and throughout the body. If overproduced by the immune system in response to another condition this can produce a ‘cytokine storm’ effect.

A large molecule that acts as the hereditary material by carrying information coding for all the characteristics and functions of an organism.

The most common and severe type of Adverse Drug Reaction and is a common cause of liver failure. DILI is difficult to predict in new, or existing populations because it only affects a small percentage of the population. It is thought to be mediated by the individual’s immune system and influenced by their genetics.

How effectively a drug produces the desired result. Animal tests are used to give an indication of the efficacy as well as safety of the candidate drug.

“Normative” i.e. how things should or ought to be, how to value them, which things are good or bad, which actions are right or wrong.

  • Animal ethics: whether we ought to do something or with welfare, how we ought to do something.

Investigations to discover something new, prove an idea or test a hypothesis.

A pre-planned set of methods devised to answer a research question without bias or error. Experimental design is particularly important in animal research to ensure animal numbers required are reduced to a minimum and welfare prioritised whilst allowing the scientific objectives to be met.

Learn more about experimental design.

An animal that has been genetically modified.

Learn more about the use of genetically altered non-human primates in research.

Changing animals, by inserting, mutating or deleting genes or parts of chromosomes. These animals are said to be genetically altered (GA).

A supporting document providing detailed guidance on how ASPA should be administered and enforced. It includes further details on what constitutes a regulated procedure, what animals are protected, licensing requirements, principles of the 3Rs, euthanasia methods, rehoming and re-release, housing and husbandry, AWERBs, inspections, and penalties for non-compliance.

Learn more about ASPA and its surrounding regulation.

Showing concern for animal well-being.

Identifying the earliest point at which a procedure will be ended to minimise pain, distress or discomfort, whilst allowing the scientific objectives of the research to be met. While humane endpoints often result in the euthanasia of an animal, they are set as an endpoint to a procedure, not an animal, and can also be applied in the form of predetermined pain relief.

Learn more about what a humane endpoint is.

A complex system involving protective cells, tissues and organs in the body, which specifically recognise and destroy foreign organisms which otherwise could cause harm.

Antibody-based methods that allow the measurement of very small quantities of substances, such as cytokines or hormones, in blood samples.

Genetically similar animals, produced as a result of the repeated mating of closely related animals. (See Outbred strain).

Substances that are used to make a finished product.

Methods that use computers, mathematical models and simulations to predict, for example, human responses to a compound, or to model the progression of disease and treatments within the human population.

‘In glass’ experiments are carried out outside the body of an animal, in for example a test tube or culture dish. In vitro research is generally referred to as the manipulation of organs, tissues, cells, and biomolecules in a controlled, artificial environment. The characterisation and analysis of biomolecules and biological systems in the context of intact organisms is known as in vivo research.

The characterisation and analysis of biomolecules and biological systems in the context of intact organisms is known as in vivo research.

Reversible damage to tissues, such as the eye and skin, causing redness and soreness.

Brain imaging technique which detects signals given out by the brain when a person is awake and records them as an image on a computer.

Chemical and physical processes within the body that alter a chemical.

Genetically nonidentical animals, produced by breeding at random or selecting parents that are not closely related. (See inbred strain).

A concept linked to the implementation of the 3Rs where suffering is reduced in experiments by using for example an invertebrate species (such as flies, moths or worms) that are not perceived to be sentient, or therefore suffer in the same way a mammal might. This term is also used where animals have been killed with the sole aim of providing primary animal tissue for research. These animals will not have been used or suffered in any regulated scientific procedures prior to this.

A progressive nervous disease occurring most often after the age of 50, linked with the destruction of brain cells that produce dopamine. Symptoms include muscular tremor, slow movement, partial facial paralysis, strange posture and weakness.

Learn more about human-relevant approaches to studying Parkinson’s.


Literally “after death”. An examination of a dead body to discover the cause of death.

A test or experiment.

Animals are protected under ASPA. Vertebrates (i.e. animals with backbones), other than humans, from halfway through their development in the womb (mammals) or egg (birds and reptiles), or when they are able to feed by themselves (amphibians and fish). Cephalopods (octopuses and squids) are also protected.

Refinement techniques reduce the amount of pain and distress caused to laboratory animals to an absolute minimum.

Learn more about the 3Rs.

Replacement alternatives can be defined as methods, strategies and techniques, such as cell culture, that do not require live animals.

Learn more about the 3Rs.

Any procedure applied to a protected animal for a qualifying purpose, such as any scientific, research, testing, or educational purpose. Also referred to as a scientific or animal procedure.

Learn more about what’s meant by a ‘procedure’ in animal research.

A list of humane methods of killing laboratory animals and approved means of confirming that the animals are deceased. Schedule 1 killings are not regulated procedures and therefore do not require a project license to perform. The method of killing used depends on the species, size and age of the animal.

Learn more about Schedule 1 killings.


A section within the Animals (Scientific Procedures) Act 1986 concerning the protection of confidential information. Under Section 24, the Home Office cannot release any information received in confidence under ASPA.

Learn more about what Section 24 is.


Able to feel pain and suffer depending on how well-developed the nervous system is.

The 3Rs stands for the principles of Replacement, Reduction and Refinement, as alternatives to the conventional use of animals in laboratory-based research.

The 3Rs are used worldwide by universities and legislators so it’s a helpful phrase to know. The 3Rs’ primary aim is to replace animals with non-animal methods where possible. There’s also a commitment to improve animal welfare where animal use is deemed unavoidable by regulatory bodies or researchers

The 3Rs stand for: 

  • Replacement – Where alternative techniques, methods and strategies are available that do not require live animals, they should be used instead
  • Reduction – Refers to the reduction of animals being used in an experiment to the minimum required to achieve the aims 
  • Refinement – Refers to the requirement to refine experimental procedures and husbandry practices to minimise pain, suffering and distress for the animals involved 


Level of poisonousness; potential to cause harm.

Taking tissue or a whole organ, such as a kidney, from a donor individual and surgically introducing it into the body of a patient to replace a defective tissue or organ.

Read about our views on xenotransplantation.

Carrying out surgical experiments on living animals.


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