Release Notes 2025-12-17 Ontology content summary Metric Value Number of subclasses of root 3228 Number of annotations on CL terms 16661 Number of synonyms 6859 Number of unique references 1960 Number of unique references in definitions 2015 Number of relationships with CL term as subject 4826 Number of cellxgene classes 1026 Number of HRA classes 515 CL Links from External Ontologies (This summary focuses on relationships to CL terms in major importers of CL, it is not a comprehensive report of all such relationships) UBERON → CL (count: 1388) GO → CL (count: 2099) HPO → CL (count: 145) MONDO → CL (count: 184) Click here for a complete current summary release report What's Changed Generalize chondrocyte definition and add skeletogenic cell parent by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3466 Add fibrochondrocyte (CL_4072104) term by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3467 Add osteochondral skeletal stem cell (CL_9900001) by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3490 Add M0 macrophage term and promote M1/M2 to primary labels by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3438 Adds OLS MCP to work in VSC by @aleixpuigb in https://github.com/obophenotype/cell-ontology/pull/3416 Add proliferative fibrochondrocyte cell type term by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3487 Add regulatory chondrocyte (RegC) term CL_9900001 by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3488 Add homeostatic chondrocyte term (CL_9900001) by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3489 Added IgD-negative class switched memory B cell by @Caroline-99 in https://github.com/obophenotype/cell-ontology/pull/3512 Add fibrochondrocyte progenitor cell (CL_9900000) by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3505 Update hypertrophic chondrocyte (CL:0000743): remove "terminally differentiated", add UBERON and GO links by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3507 Add prehypertrophic chondrocyte term (CL_9900000) by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3508 Add effector chondrocyte term (CL_9900000) by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3503 Update CLAUDE.md with editing and metadata guidelines by @dosumis in https://github.com/obophenotype/cell-ontology/pull/3446 Add new term CL_9900001 - alpha retinal ganglion cell OFF-sustained by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3501 Add alpha retinal ganglion cell ON-sustained - closes #3492 by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3504 Add new term CL:9900001 alpha retinal ganglion cell OFF-transient by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3509 Refine definition of direct pathway medium spiny neuron (CL_4023026) by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3482 Add alpha retinal ganglion cell ON-transient (CL_9900001) by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3510 Revise definition of indirect pathway medium spiny neuron (CL_4023029) by @Copilot in https://github.com/obophenotype/cell-ontology/pull/3484 Refreshed imports for Dec25 release by @RiveraAndrea83 in https://github.com/obophenotype/cell-ontology/pull/3538 Release files for 20251217 by @RiveraAndrea83 in https://github.com/obophenotype/cell-ontology/pull/3539 Full Changelog: https://github.com/obophenotype/cell-ontology/compare/v2025-11-27...v2025-12-17