Fibrocytes

Fibrocytes form a three-dimensional network with their cell processes and thus stabilize the connective tissue which is composed of collagen. Fibrocytes are the dormant form of fibroblasts. You do not produce fibers for the extracellular matrix yourself.

Only when the tissue is traumatised can fibrocytes be transformed into fibroblasts again and produce fibres and release them into their environment.

https://de.wikipedia.org/wiki/Fibrozyt _{(Wikipedia CC-by-sa-3.0)}