It is possible that some subclasses are an accident of the tendency of some people to use this term synonymously with 'fibroblast'. This is very clearly the case for tendon cells (tenocytes) which are definitely not quiescent and do not have the structure described in the definition of tenocyte.
Should there be some relationship to fibroblast or GO term for fibroblast differentiation?
Logical axioms make assertions about function that are not reflected in the textual definition. These should be researched and added to the text definition if correct.
fibrocyte http://purl.obolibrary.org/obo/CL_0000135 An inactive fibroblast; cytoplasm is sparse, endoplasmic reticulum is scanty with flattened nucleus. Term used by some histologists; when fibroblasts become relatively inactive in fiber formation. However, this cell has the potential for fibrogenesis in quiescent connective tissue of the adult, as well as during development, other histologists prefer to use the term fibroblast in all circumstances. These cells represent ~0.5% of peripheral blood leukocytes. EquivalentTo: (stromal cell and capable of some antigen processing and presentation of peptide antigen via MHC class II and capable of some positive regulation of angiogenesis)