fibroblast quiescent fibroblast 2025-08-13T15:42:37Z A fibroblast in a quiescent state, characterized by a smaller, spindle-shaped morphology with a relatively small cytoplasm, modest rough endoplasmic reticulum and condensed chromatin. Despite low proliferation and contractility, it maintains high metabolic activity for extracellular-matrix homeostasis through continuous matrix protein turnover and mechanosensitive signaling. This cell can rapidly differentiate into contractile myofibroblasts under injury or inflammatory cues to drive tissue repair. Historically, quiescent fibroblasts in uninjured tissues were often called “fibrocytes”, but this distinction faded over time, and the term “fibroblast” came to be used universally, regardless of activation state. Fibrocyte has been repurposed to describe a distinct population of bone marrow–derived, circulating cells that home to sites of injury and contribute to tissue repair and fibrosis. inactive fibroblast