Table 2.

Comparative ultrastructural features of fibroblasts, smooth-muscle cells and myofibroblasts^*

	Fibroblast	Smooth-muscle cell	Myofibroblast
Rough endoplasmic reticulum	Abundant	Scarce	Abundant
Collagen secretion granules	Present	Absent	Present
Smooth-muscle myofilaments†	Absent	Abundant	Slender, peripheral bundles
External lamina	Absent	Present	Absent
Focal adhesion‡	Present	Absent	Absent
Fibronexus	Absent	Absent§	Conspicuous
Nuclear irregularity	Smooth	Irregular	Mostly smooth
Cell-surface irregularity	Smooth	Small-scale irregularities¶	Smooth

^*Granulation tissue and tumour stromal myofibroblasts.

^†With focal densities.

^‡Also and originally called subplasmalemmal linear densities[40].

^§Present in aortic smooth-muscle cells but extremely attenuated [41].

^¶See, for example, references [33, 42].