Braverman IM
The Journal of investigative dermatology. Date of publication 1989 Aug 1;volume 93(2 Suppl):2S-9S.
1. J Invest Dermatol. 1989 Aug;93(2 Suppl):2S-9S.
Ultrastructure and organization of the cutaneous microvasculature in normal and
pathologic states.
Braverman IM(1).
Author information:
(1)Department of Dermatology, Yale University School of Medicine, New Haven,
Connecticut 06510.
The cutaneous microvasculature is organized into upper and lower horizontal
plexuses with the dermal capillary loops arising from the upper plexus. The
arteriolar and venular sides of the microvasculature can be identified by the
ultrastructure of the mural basement membrane material. Collecting venules
present in the lower dermis contain valves. Periadventitial cells (veil cells)
are present around all microvessels. Their size and number appear to correlate
with the quantity of mural basement membrane material found in cutaneous vessels
in diabetes, actinic damage, and chronological aging. The contractile cells of
the vascular wall surround the endothelial cell tube in a manner suggesting
specific functions. The smooth muscle cells in the arteriolar segment form a
sleeve, whereas each pericyte in the postcapillary venular simultaneously makes
many contacts with several underlying endothelial cells. The common
telangiectases can be explained by abnormalities in this organization and
ultrastructure rather than by neovascularization or random anastomoses. The
macular telangiectases seen in scleroderma, generalized essential telangiectasia,
and nevus flammeus are produced by dilatation of the postcapillary venules of the
upper horizontal plexus. Cherry angiomas are produced by spherical and tubular
dilatations of capillary loops in dermal papillae with tortuous cross-connections
between individual loops. Angiokeratomas of Fabry and Fordyce have the
ultrastructure of collecting venules that contain valves, and appear to represent
the ectopic development or placement of small valve-containing collecting veins.
The cutaneous lesions of hereditary hemorrhagic telangiectasia represent
arteriovenous communications.
DOI: 10.1111/1523-1747.ep12580893
PMID: 2666519 [Indexed for MEDLINE]
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