Both types are in close contact with the endothelial cells lining the capillaries, and are important for vascular development and stability.
[4] Pericytes, vSMCs, and many other perivascular cell types [clarification needed] express very similar markers such as Platelet Derived Growth Factor Receptor Beta (PDGFR-B), aminopeptidase-N (CD13), chondroitin sulfate proteoglycan 4 (Ng2), or desmin, which makes their identification difficult and requires a combination of markers: for example vSMCs but not pericytes express alpha-smooth muscle actin (ACTA2).
Typically, vSMCs wrap around larger vessels: they form a dense continuum spindling around arteries, arterioles and precapillary arterioles; while around postcapillary venules, vSMCs adopt a different morphology: individual cell bodies extending thing branching processes, that become more stellate-like around venules and veins.
The cell body of pericytes has a round shape extending a few processes in a longitudinal fashion along the capillaries.
[5] This showed that there is a zonation in their expression patterns by which they can be grouped into different subsets, but no singular markers have been found so far that can identify unequivocally any of the cell types.