All types of the disease share the same clinical presentation due to unregulated generation of bradykinin causing leakage of plasma from postcapillary venules
These telangiectasias, the hallmark of the disease, arise from the dilatation of postcapillary venules
, which directly fuse with an arteriole, thus bypassing the capillary system.
The excessive accumulation of neutrophils in the postcapillary venules
during inflammation causes clogging of the vessels; therefore, there is a decrease in tissue perfusion (3).
drain caudally into veins of the posterior group of the medial nasal glands (Figs.
Also, it is well accepted that Th2-derived interleukin-5 (IL-5) plays a key role in developing and maturing of eosinophils, enhancing their adhesion to endothelial cells lining the postcapillary venules
, activating, secreting, and prolonging survival through apoptosis inhibition in the tissues .
Senile hemangioma or CA is a vascular tumor which consists of proliferated small vascular channels which have been originated from postcapillary venules
in the upper dermis and it has been mentioned that CA should not be considered as a neovascularization .
HSP, also known as anaphylactoid purpura and immunoglobulin A (IgA) vasculitis, is a small-vessel leukocytoclastic vasculitis characterized by the perivascular deposition of IgAl-based immune complexes in the walls of arterioles and postcapillary venules
. (1) The clinical picture of HSP is palpable purpura, abdominal pain, arthritis, and hematuria 1-2 weeks following an upper respiratory infection.
Under physiological conditions, naive (i.e., mature, non-activated) lymphocytes migrate from the peripheral blood into lymph nodes and Peyer's patches by selectively interacting with the specialized endothelium of postcapillary venules
called high endothelial venules (HEVs).
Circulating naive T cells migrate to the parenchyma of draining lymph nodes through specialized postcapillary venules
called high endothelial venules (HEVs) (Figure 1).
Three to five postcapillary venules
per mouse were recorded (4-6 mice per group) (1 min 20 seconds each venule) and cell adhesion quantified from one minute of the recording.
Pericytes embedded within the basement membrane of capillaries and postcapillary venules
play an important role in endothelial cell proliferation, migration, and stabilization .
Thus the T-cells and the blood vessels, mainly postcapillary venules
, may be induced to proliferate.