ARRIVE Essential - Experimental procedures

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​​DISCLAIMER: Information on this and related pages is based on or copied directly from the ARRIVE guidelines 2019 (please see the original guidelines for more information, references and examples that are not included on these pages):

ARRIVE Essential 10 - Item 9 - Experimental procedures

For each experimental group, including controls, describe the procedures in enough detail to allow others to replicate them, including:

9a. What was done, how it was done and what was used.

Essential information to describe in the manuscript includes the procedures used to develop the model (e.g. induction of the pathology), the procedures used to measure the outcomes, and pre- and post-experimental procedures, including animal handling and welfare monitoring. Animal handling can be a source of stress and the specific method used (e.g. mice picked up by tail or in cupped hands) can affect research outcomes. Details about animal care and monitoring intrinsic to the procedure are discussed in further detail in item 16 – Animal care and monitoring. Provide enough detail to enable others to replicate the methods and highlight any quality assurance and quality control used. A schematic of the experimental procedures with a timeline can give a clear overview of how the study was conducted. The ARRIVE guidelines 2019 online contain additional information relevant to distinct types of interventions and resources (Item 9 - Box 6 here).​

Where available, cite the Research Resource Identifier (RRID) for reagents and tools used. RRIDs are unique and stable, allowing unambiguous identification of reagents or tools used in a study, aiding other researchers to replicate the methods.

Detailed step-by-step procedures can also be saved and shared online, for example using, which assigns a DOI to the protocol and allows cross-referencing between protocols and publications.

9b. When and how often.

Clearly report the frequency and timing of experimental procedures and measurements, including the light and dark cycle (e.g. 12:12), circadian time cues (e.g. lights on at 08:00), and experimental time sequence (e.g. interval between baseline and comparator measurements or interval between procedures and measurements). Along with innate circadian rhythms, these can affect research outcomes such as behavioural, physiological, and immunological parameters. Also report the timing and frequency of welfare assessments, taking into consideration the normal activity patterns. For example, nocturnal animals may not show behavioural signs of discomfort during the day.​

9c. Where (including detail of any acclimation periods).

Physiological acclimation after a stressful event, such as transport (e.g. between supplier, animal facility and laboratory), but before the experiment begins allows stabilisation of physiological responses of the animal. Protocols vary depending on species, strain, and outcome; for example physiological acclimation following transportation of different animals can take anywhere from 24 hours to more than one week. Procedural acclimation, immediately before a procedure, allows stabilisation of the animals’ responses after unaccustomed handling, novel environments, and previous procedures, which otherwise can induce behavioural and physiological changes.

Indicate where studies were performed (e.g. dedicated laboratory space or animal facility, home cage, open field arena, water maze) and whether periods of physiological or procedural acclimation were included in the study protocol, including type and duration. If the study involved multiple sites explicitly state where each experiment and sample analysis was performed. Include any accreditation of laboratories if appropriate (e.g. if samples are sent to a commercial laboratory for analysis).

9d. Why (provide rationale for procedures).

There may be numerous approaches to investigate any given research problem, therefore it is important to explain why a particular procedure or technique was chosen. This is especially relevant when procedures are novel or specific to a research laboratory, or constrained by the animal model or experimental equipment (e.g. route of administration determined by animal size).

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