egg cell
Enable an AI agent to recognise an egg cell, assess its developmental and physical state, and identify which observations or interventions are appropriate under the applicable biological and governance constraints.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to recognise an egg cell, assess its developmental and physical state, and identify which observations or interventions are appropriate under the applicable biological and governance constraints.
The egg cell (ovum) is the non-motile female gamete of oogamous organisms: a large, cytoplasm-rich germ cell produced by oogenesis that, at the fertilizable stage, fuses with a sperm to form a zygote and supplies the maternal genome, mitochondria and most of the zygote's cytoplasm.
It can be Identify and track an individual egg cell while preserving its source and handling links.; Observe and measure organism-specific maturation and condition indicators.; Assess readiness for a proposed intervention against explicit evidence and prerequisites.; Select an applicable protocol for collection, culture, maturation or preservation when authorised.; Record authorised fertilisation or activation attempts and evaluate their observed outcomes.; Transfer ownership to a fertilised-cell or embryo model when the declared boundary is met..
Distinguishing features
Require evidence identifying the entity as a female germ cell in its organism's reproductive system; shape or size alone does not distinguish it from a somatic cell.
Distinguish the individual cell from a follicle or cell complex by locating the egg-cell boundary and recording which surrounding structures remain attached.
Distinguish an egg cell from a whole laid egg by identifying whether the record concerns the cell itself or the larger reproductive package.
Distinguish maturation stages using organism-appropriate evidence rather than treating every object labelled 'egg' as a mature ovum.
Distinguish an unfertilised egg cell from a fertilised or activated cell using recorded observations and an explicit transition criterion.
Scope
+ Identification of an individual egg cell and its organism of origin
+ Oocyte or ovum terminology and developmental stage in the relevant organism
+ Cell contents, coverings and associated cells needed to interpret condition
+ Evidence about integrity, viability and fertilisation competence
+ Collection, culture, storage, preservation and handling history
+ Permitted interventions and transition to a fertilised-cell model
- The donor organism's overall reproductive health and clinical care
- Ovarian follicles and reproductive organs as independently managed structures
- Sperm cells and their independent quality assessment
- Zygote and embryo development after the model's fertilisation boundary
- Whole laid eggs, including shell, albumen and other packaging
- Laboratory equipment, treatment plans and consent instruments as independent entities
Characteristics
- Organism and reproductive context
- Linked organism or taxon; reproductive context; identification confidence Determines which terminology, structures, developmental stages and handling rules apply.
- Cell identity and origin
- Individual specimen identifier; source organism or sample reference; collection event Prevents substitution and connects observations to the correct cell.
- Developmental designation
- Organism-specific germ-cell stage; original label; classification scheme; unknown Separates established identity from ambiguous uses of 'egg', 'oocyte' and 'ovum'.
- Meiotic state
- Organism-appropriate stage; observation method; assessment time; indeterminate Supports interpretation of maturation and eligibility for stage-dependent interventions.
- Cell dimensions
- Micrometres or millimetres; measured axes; inclusion or exclusion of coverings Supports recognition and comparison without conflating cell size with surrounding structures.
- Coverings and associated cells
- Organism-specific structures; present, absent, removed, disrupted or unassessed Affects what can be observed and how the cell can be handled.
- Integrity and morphology
- Recorded membrane, cytoplasmic and covering observations; assessment method and time Provides evidence of condition while preserving the distinction between appearance and function.
- Viability and functional competence
- Separate viability, maturation and fertilisation assessments; supporting evidence; uncertainty Prevents one favourable observation from being treated as proof of every relevant capability.
- Preservation state
- Fresh, cultured, cryopreserved, warmed, fixed or other documented state Changes the available observations, possible interventions and interpretation of condition.
- Fertilisation and activation status
- No evidence observed, suspected, confirmed or indeterminate; fertilisation and activation assessed separately Determines whether egg-cell actions remain appropriate and whether another model must take ownership.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 28 questions.
Egg-cell identity Establishes what entity is being called an egg cell and which biological interpretation applies.
Egg terminology can refer to different stages or larger structures, so action requires a precise referent.
Biological identification
Connects identification to organism-specific evidence and terminology.
Identity evidence
Record the basis for identifying this specimen as an egg cell and retain uncertainty in that identification.
- What observations or source records identify this entity as an egg cell rather than another germ cell or a somatic cell? definition
- Which organism and reproductive context support that identification? provenance
Cell and surroundings
Separates the cell from attached structures and reproductive packaging.
Physical referent
Record what belongs to the cell record and what is represented through related structures.
- Does this record identify an individual cell, a cell with associated coverings or cells, or a larger structure incorrectly labelled as the cell? boundary
- Which coverings or associated cells are present, and were any removed during preparation? provenance
Egg-cell maturation Records developmental designation, meiotic evidence and readiness for stage-dependent actions.
An egg-cell label alone does not establish maturity or suitability for a reproductive procedure.
Developmental stage
Interprets maturation using the relevant organism's classification.
Stage assignment
Record the assigned stage, the evidence supporting it and any limits of observation.
- Which developmental and meiotic stages are assigned under the selected organism-specific classification? definition
- What observable features or assays support those assignments, and when were they assessed? measurement
Maturation readiness
Separates stage classification from evidence of functional readiness.
Readiness for the next step
Record which maturation requirements a proposed intervention depends on and whether each is established.
- What evidence supports cytoplasmic or other functional maturation beyond the assigned meiotic stage? measurement
- Which maturation prerequisites remain unmet or unknown for the proposed culture, preservation or fertilisation step? action
Egg-cell condition Organises observations of structure, damage, viability and functional potential.
Decisions must distinguish directly observed condition from predictions about reproductive performance.
Structural observations
Captures interpretable measurements of the cell and its relevant structures.
Morphology and integrity
Record dimensions and visible condition using explicit measurement boundaries and assessment methods.
- What are the measured cell dimensions, and do those measurements include any coverings? measurement
- What membrane, cytoplasmic or covering abnormalities were observed, using which method and at what time? measurement
Functional assessment
Keeps viability and reproductive competence distinct and evidence-bound.
Competence evidence
Record what each assessment establishes, what it merely predicts and what remains unknown.
- Which observations or assays support viability, and which separately support maturation or fertilisation competence? measurement
- Which proposed actions are justified by that evidence, and which require further assessment? action
Egg-cell handling Tracks identity through collection and manipulation and relates current condition to handling exposures.
An egg cell's action eligibility depends on both its biological state and the procedures already performed on it.
Collection and continuity
Maintains the connection between the individual cell, its source and subsequent observations.
Specimen continuity
Record collection and transfers without claiming individual continuity when only a group was tracked.
- From which organism, tissue or source sample was the cell obtained, and by which collection procedure? provenance
- Was this individual tracked continuously, or do any observations apply only to its collection group? boundary
Culture and preservation
Records exposures and interventions relevant to interpreting the current cell state.
Handling-dependent state
Link culture, preservation and manipulation events to applicable protocols and subsequent assessments.
- What media, temperatures, durations, preservation cycles and manipulations are documented for this cell? provenance
- Which protocol and post-handling observations support the next proposed manipulation? action
Egg-cell action and transition Determines permissible next steps and recognises when the entity leaves egg-cell scope.
Biological readiness, authorisation and evidence of fertilisation or activation must all inform action selection.
Intervention eligibility
Connects a proposed use to biological prerequisites and applicable permissions.
Permitted next intervention
Record the decision basis for an intervention through linked protocols and authorisation records.
- What biological prerequisites must be met for the proposed observation, maturation, preservation, fertilisation or other use? action
- Which linked authorisations and use restrictions apply to this cell and the proposed intervention? action
Fertilisation and activation boundary
Separates attempted procedures from observed biological transitions.
Transition evidence
Record fertilisation and activation evidence separately and apply an explicit ownership boundary.
- What observations establish or leave uncertain fertilisation and activation following any attempted procedure? measurement
- Which organism-specific criterion transfers this entity to a fertilised-cell or embryo model, and has that criterion been met? boundary
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Primary oocyte (dictyate/prophase I, germinal vesicle; not fertilizable)
- Secondary oocyte / metaphase-II egg (first polar body present; the fertilizable mammalian egg)
- Ovum/ootid after completion of meiosis II (haploid 1C; in mammals only minutes after sperm entry)
- Oogonium (mitotic precursor that differentiates into primary oocytes)
- ART nuclear-maturity classes: germinal vesicle (GV), metaphase I (MI), metaphase II (MII)
- Oosphere (non-motile female gamete of some algae, fungi, oomycetes and bryophytes; fertilized form is an oospore)
- Giant oocyte (about twice normal volume, often tetraploid; excluded from IVF)
- Cumulus-oocyte complex versus denuded oocyte (clinical retrieval and handling states)
- Which of these kinds and varieties hold for the sense of egg cell this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Wikidata - Q1321695 - Item labelled egg cell / ovum; marked different from oocyte.
- Cell Ontology - CL:0000025 - Recorded on Wikidata as CL_0000025.
- Foundational Model of Anatomy - FMA:67343 - Named Ovum.
- ICD-11 MMS - XA95A3 - Female gamete (anatomy extension code, not a disease code).
- ICD-11 Foundation - 1641279043 - Foundation entity linked to female gamete.
- MeSH - D009865 - Oocyte, the immature/ovarian stage rather than the mature ovum.
- FMA (oocyte) - FMA:18644 - Anatomical identifier for oocyte, not ovum.
- Which of these identifiers and schemes hold for the sense of egg cell this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- ESHRE and Alpha Scientists in Reproductive Medicine - Istanbul Consensus (2011) and Istanbul Consensus update (Human Reproduction, 2025) on morphological assessment of oocytes in ART.
- European Parliament and Council - Directive 2004/23/EC on quality and safety of human tissues and cells, explicitly covering reproductive cells (ova); to be replaced by Regulation (EU) 2024/1938 from 6 August 2027.
- Which of these standards and regulation hold for the sense of egg cell this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Released at ovulation into the oviduct, where it is either fertilized or degenerates and is reabsorbed.
- Retrieved as a cumulus-oocyte complex in IVF/ICSI, stripped, graded (GV/MI/MII and dysmorphisms), then inseminated or injected.
- Cryopreserved (oocyte banking) for later thaw and fertilization.
- Donated under tissue-and-cell rules for recipient treatment cycles.
- Used in research on meiosis, aneuploidy and early embryo chromosome segregation.
- Which of these real-world use hold for the sense of egg cell this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Human MII cytoplasmic diameter (excluding zona pellucida) - 110-120 - µm
- Human preovulatory oocyte diameter including zona pellucida - about 150 - µm
- Human zona pellucida thickness - 15-20 (reported span 10-31) - µm
- Giant-oocyte diameter (ART exclusion threshold) - >180 - µm
- Small-oocyte cytoplasmic diameter (poor developmental potential) - <100 - µm
- Chromosome number in secondary oocyte / ovum - 23 (always 23,X) - chromosomes
- Fertilizable lifespan after ovulation (human) - 12-24 - h
- Which of these typical measurements hold for the sense of egg cell this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Meiotic chromosome mis-segregation (nondisjunction or premature sister-chromatid separation), rising with maternal age, producing aneuploid embryos.
- Postovulatory aging beyond about 24 hours: spindle disruption, polar-body degeneration, zona changes, lower fertilization and poorer embryos.
- Failed cortical/zona block allowing polyspermy.
- Giant (often tetraploid) oocytes, which ESHRE/ALPHA recommend excluding from IVF/ICSI.
- Very small oocytes and severe cytoplasmic or zona dysmorphisms with low developmental competence.
- Atresia: most ovarian oocytes never ovulate and degenerate over the reproductive lifespan.
- Unfertilized ovulated oocyte breaks down and is reabsorbed.
- Which of these failure modes and hazards hold for the sense of egg cell this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Mammalian cell-biology English distinguishes ovarian 'oocyte' from oviductal fertilizable 'egg'; clinical English often calls both an egg.
- Some plant, algal and fungal literature names the homologous cell an oosphere rather than an ovum.
- In the EU, donated ova are regulated as tissues and cells under Directive 2004/23/EC (until replacement by Regulation (EU) 2024/1938 in 2027); other jurisdictions use separate ART statutes not read here.
- Which of these regional variation hold for the sense of egg cell this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Oocyte (immature female germ cell) - In mammals, an oocyte is ovarian and arrested in prophase I with an intact nucleus; an egg is oviductal, MII, lacks a nucleus, shows a first polar body, and can be fertilized (Duncan criteria).
- Ovarian follicle - The follicle is the somatic sac that contains the oocyte; ultrasound counts follicles, not free egg cells.
- Polar body - A minute meiotic product with almost no cytoplasm; it is not a gamete capable of supporting an embryo.
- Spermatozoon - The motile male gamete, far smaller, haploid 23,X or 23,Y; the egg is non-motile and always 23,X.
- Zygote - The fertilized cell after sperm-egg fusion, marked by two pronuclei and completion of meiosis II; an unfertilized egg has one maternal genome only.
- Plant ovule - The ovule is the organ that houses the embryo sac; the egg cell is one cell inside that sac.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of egg cell this model covers, and on what evidence? provenance
Sources
- Eggs (Molecular Biology of the Cell, 4th ed., Ch. 20) - Oocyte-to-ovum stages, meiotic arrests, polar bodies, and species differences in when meiosis completes.
- Unscrambling the oocyte and the egg: clarifying terminology of the female gamete in mammals - Functional distinction of mammalian oocyte (prophase I, ovary) from egg (MII, oviduct, fertilizable).
- Ovum (Egg Cell): Structure, Function & Fertilization - Human ovum as female gamete; ovulation, fertilization to zygote, or breakdown if unfertilized; haploid 23 chromosomes.
- Egg cell - Non-motile female gamete in anisogamy/oogamy; oosphere in some plants and fungi; mammalian ovum size and discovery history.
- egg cell (Q1321695) - Identifiers: Cell Ontology CL_0000025, FMA 67343, ICD-11 XA95A3, and distinction from oocyte.
- The Istanbul consensus update: a revised ESHRE/ALPHA consensus on oocyte and embryo static and dynamic morphological assessment - ART morphology criteria; small, large and giant oocyte size cut-offs; exclusion of giant oocytes; polar-body and zona findings.
- Safe human tissues & cells for transplantation (until 2027) - summary of Directive 2004/23/EC - EU quality and safety law covering donation and processing of ova; replacement by Regulation (EU) 2024/1938 from 6 August 2027.
- Egg Transport and Fertilization (Volume 5, Chapter 46) - Human oocyte fertilizable lifespan of about 12-24 hours; zona pellucida as species-selective barrier and block to polyspermy.
What the second pass must settle
- Does the registry intend 'egg cell' to cover immature oocytes and plant egg cells as well as mature animal ova, and how should that breadth be expressed without splitting the entry?
- Which organism-specific maturation classifications and observable indicators should be supported as authoritative extensions?
- Which viability and competence assessments are sufficiently validated for each intended use, and which alter or consume the cell being assessed?
- What exact ownership boundary should apply to fertilisation, activation without fertilisation and indeterminate transition states?
- Which existing Vercy models already own this concept or its neighbouring structures, and which protocol and authorisation models should be linked?