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Key Event: 2413

Key Event Title

A descriptive phrase which defines a discrete biological change that can be measured. More help

Increased, uterine weight

Short name

The KE short name should be a reasonable abbreviation of the KE title and is used in labelling this object throughout the AOP-Wiki. More help

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Biological Context

Structured terms, selected from a drop-down menu, are used to identify the level of biological organization for each KE. More help

Level of Biological Organization
Organ

Organ term

The location/biological environment in which the event takes place.The biological context describes the location/biological environment in which the event takes place. For molecular/cellular events this would include the cellular context (if known), organ context, and species/life stage/sex for which the event is relevant. For tissue/organ events cellular context is not applicable. For individual/population events, the organ context is not applicable. Further information on Event Components and Biological Context may be viewed on the attached pdf. More help

Organ term
uterus

Event Components

The KE, as defined by a set structured ontology terms consisting of a biological process, object, and action with each term originating from one of 14 biological ontologies (Ives, et al., 2017; https://aopwiki.org/info_pages/2/info_linked_pages/7#List). Biological process describes dynamics of the underlying biological system (e.g., receptor signalling).Biological process describes dynamics of the underlying biological system (e.g., receptor signaling). The biological object is the subject of the perturbation (e.g., a specific biological receptor that is activated or inhibited). Action represents the direction of perturbation of this system (generally increased or decreased; e.g., ‘decreased’ in the case of a receptor that is inhibited to indicate a decrease in the signaling by that receptor). Note that when editing Event Components, clicking an existing Event Component from the Suggestions menu will autopopulate these fields, along with their source ID and description. To clear any fields before submitting the event component, use the 'Clear process,' 'Clear object,' or 'Clear action' buttons. If a desired term does not exist, a new term request may be made via Term Requests. Event components may not be edited; to edit an event component, remove the existing event component and create a new one using the terms that you wish to add. Further information on Event Components and Biological Context may be viewed on the attached pdf. More help

Process	Object	Action
increased uterus weight	body of uterus	increased

Key Event Overview

AOPs Including This Key Event

All of the AOPs that are linked to this KE will automatically be listed in this subsection. This table can be particularly useful for derivation of AOP networks including the KE.Clicking on the name of the AOP will bring you to the individual page for that AOP. More help

AOP Name	Role of event in AOP	Point of Contact	Author Status	OECD Status
Activation, ERα leads to increased uterine weight via earlier proliferation of cells	AdverseOutcome	John Frisch (send email)	Under development: Not open for comment. Do not cite

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) that help to define the biological applicability domain of the KE.In many cases, individual species identified in these structured fields will be those for which the strongest evidence used in constructing the AOP was available in relation to this KE. More help

Term	Scientific Term	Evidence	Link
mammals	mammals	High	NCBI

Life Stages

An indication of the the relevant life stage(s) for this KE. More help

Life stage	Evidence
Adult, reproductively mature	Moderate
Juvenile	Moderate

Sex Applicability

An indication of the the relevant sex for this KE. More help

Term	Evidence
Female	High

Key Event Description

A description of the biological state being observed or measured, the biological compartment in which it is measured, and its general role in the biology should be provided. More help

Increased uterine weight is physiological development associated with reproductive maturity of an individual, with organisms exposed to a stressor exhibiting increase in uterine weight at an abnormal age or to an unusual level (Goldman et al. 2008). Uterine weight increases due to proliferation of cells, particularly endometrial epithelial (lining) cells, causing an increase in uterine lining thickness (Nicklaus et al. 2007).

How It Is Measured or Detected

A description of the type(s) of measurements that can be employed to evaluate the KE and the relative level of scientific confidence in those measurements.These can range from citation of specific validated test guidelines, citation of specific methods published in the peer reviewed literature, or outlines of a general protocol or approach (e.g., a protein may be measured by ELISA). Do not provide detailed protocols. More help

Uterine weight is measured directly after surgical removal, generally during necropsy.

Uterine weight can be estimated non-destructively by ultrasound or MRI scan (Harb and Adam 2005).

Domain of Applicability

A description of the scientific basis for the indicated domains of applicability and the WoE calls (if provided). More help

Life Stage: Adult, reproductively mature and juveniles.

Sex: Applies to females.

Taxonomic: Primarily studied in laboratory rodents. Applicable to most mammals and marsupials that have uteri and shared reproductive physiology.

Regulatory Significance of the Adverse Outcome

An AO is a specialised KE that represents the end (an adverse outcome of regulatory significance) of an AOP. More help

Increased uterine weight is an adverse outcome monitored in Endocrine Disruptor Screening Program (EDSP) protocol (US EPA 1998; US EPA 2011a; US EPA 2011b; OECD 2025).

References

List of the literature that was cited for this KE description. More help

Goldman JM, Laws SC, Balchak SK, Cooper RL, Kavlock RJ. 2008. Endocrine-Disrupting Chemicals: Prepubertal Exposures and Effects on Sexual Maturation and Thyroid Activity in the Female Rat. A Focus on the EDSTAC Recommendations. Critical Reviews in Toxicology 30(2):135-196.

Harb TS, Adam RA. 2005. Predicting uterine weight before hysterectomy: ultrasound measurements versus clinical assessment. American Journal of Obstetrics and Gynecology 193(6): 2122-2125.

Niklaus AL, Aubuchon M, Zapantis G, Li P, Qian H, Isaac B, Kim MY, Adel G, Pollard JW, Santoro NF. 2007. Assessment of the proliferative status of epithelial cell types in the endometrium of young and menopausal transition women. Human Reproduction 22(6): 1778-1788.

Organisation for Economic Co-operation and Development. 2025. Test No. 443: Extended One-Generation Reproductive Toxicity Study, OECD Guidelines for the Testing of Chemicals, Section 4, OECD Publishing, Paris. https:// https://www.oecd.org/en/publications/test-no-443-extended-one-generation-reproductive-toxicity-study_9789264185371-en.html (retrieved 11 Dec 2025)

U.S. Environmental Protection Agency (EPA), Office of Chemical Safety and Pollution Prevention. 2011a. OCSPP test guideline 890.1600: Uterotrophic assay (EPA 740-C-09-0010). https://www.epa.gov/sites/default/files/2015-07/documents/final_890.1600_uterotrophic_assay_sep_9.22.11.pdf (retrieved 11 December 2025)

US Environmental Protection Agency (EPA). 2011b. Endocrine disruptor screening program. Pubertal development and thyroid function in intact juvenile/ female rats assay. OCSPP Guideline 890.1450. Standard evaluation procedure. https://www.epa.gov/sites/default/files/2015-07/documents/final_890.1450_female_pubertal_assay_sep_8.24.11.pdf (retrieved 19 Jan 2026)

US Environmental Protection Agency (EPA). 1998. Health Effects Test Guidelines OPPTS 870.3800 Reproduction and Fertility Effects https://ntp.niehs.nih.gov/sites/default/files/iccvam/suppdocs/feddocs/epa/epa_870_3800.pdf (retrieved 19 Jan 2026)

NOTE: Italics indicate edits from John Frisch March 2026. A full list of updates can be found in the Change Log on the View History page.