Add missing growth plate chondrocyte maturation zone cell types and restructure hierarchy

[pmaye1]

Current problem:
Cell Ontology currently has "growth plate cartilage chondrocyte" (CL:0002224), "columnar chondrocyte" (CL:0000451), and "hypertrophic chondrocyte" (CL:0000563), but:

These terms are not properly hierarchically organized as developmental stages
Critical intermediate stages (resting zone, prehypertrophic) are missing
The current structure doesn't reflect the spatial/developmental zonation of the growth plate

Preferred term labels

1. resting zone chondrocyte (or resting chondrocyte)
2. proliferating chondrocyte (synonym for columnar chondrocyte)
3. prehypertrophic chondrocyte

growth plate cartilage chondrocyte (CL:0002224)
├─ resting zone chondrocyte (NEW)
├─ proliferative zone chondrocyte (could be synonym/equivalent to columnar chondrocyte CL:0000451)
├─ prehypertrophic chondrocyte (NEW)
└─ hypertrophic chondrocyte (CL:0000563) - should be child, not sibling

Synonyms (add reference(s), please)

Definition (free text, with reference(s), please. PubMed ID format is PMID:XXXXXX)
Resting zone chondrocyte:
A growth plate chondrocyte located in the resting zone that is relatively quiescent, scattered in distribution, and serves as a reservoir of skeletal progenitor cells. These cells are characterized by low proliferative activity and expression of markers including PTHrP receptor (PTH1R) and Sox9.
Prehypertrophic chondrocyte:
A growth plate chondrocyte in the transition stage between proliferative and hypertrophic zones, characterized by cell cycle exit, initial cell enlargement, and expression of markers including Indian hedgehog (IHH), PTHrP, and Runx2. These cells coordinate the transition to terminal differentiation.
Relationships:

parent term: growth plate cartilage chondrocyte (CL:0002224)
part_of: respective UBERON growth plate zones (if they exist)
develops_from: (resting → proliferative → prehypertrophic → hypertrophic progression)

PMID: 32461613 - Comprehensive review of growth plate biology
PMID: 31481583 - Single-cell analysis of growth plate chondrocyte populations
PMID: 28945871 - Growth plate zonation and chondrocyte maturation

Justification:
Growth plate chondrocytes progress through well-defined maturation zones with distinct molecular signatures, morphologies, and functions. These zones are fundamental to endochondral ossification and skeletal growth. Single-cell RNA-seq studies routinely identify these populations, and the current CL structure is insufficient for accurate annotation of growth plate datasets.

Parent cell type term (check the hierarchy here https://www.ebi.ac.uk/ols4/ontologies/cl)
growth plate cartilage chondrocyte (CL:0002224)

Anatomical structure where the cell type is found (check Uberon for anatomical structures: https://www.ebi.ac.uk/ols4/ontologies/uberon)

endochondral bone UBERON:0002513

Your ORCID
0000-0003-0098-4399

Additional notes or concerns
Additional note:
Please also consider restructuring "columnar chondrocyte" and "hypertrophic chondrocyte" as children of "growth plate cartilage chondrocyte" rather than siblings to properly reflect the developmental hierarchy.