The fibrous cap is a layer of fibrous

connective tissue Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tissue ...

, which is thicker and less cellular than the normal intima, found in atherosclerotic plaques. The fibrous cap contains

macrophages Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer ce ...

and

smooth muscle Smooth muscle is an involuntary non- striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit ...

cells. The fibrous cap of an atheroma is composed of bundles of muscle cells, macrophages, foam cells, lymphocytes, collagen and elastin. The fibrous cap is prone to rupture and ulceration which can lead to thrombosis. In advanced lesions, further complications may arise including calcification of the fibrous cap.

References

Angiology {{Pathology-stub