Soft tissue
Vascular
Normal vessels

Author: Vijay Shankar, M.D. (see Authors page)

Revised: 31 August 2016, last major update August 2016

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Normal vessels [title]
Cite this page: Normal vessels. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissuevascnormal.html. Accessed December 10th, 2016.
Definition / General
  • Normal vessels contain endothelial cells facing lumen and pericytes, smooth muscle cells and glomus cells towards outside of vessel
Diagrams / Tables

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Various Images


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Glomus cell

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Arterial wall

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Pericyte and endothelial interactions

Micro Description
Embryology:
  • Development begins with formation of hemangioblasts, which organize in blood islands in yolk sac, and differentiate into hematopoietic and angioblastic cells
  • Hematopoietic cells generate blood cells; angioblastic cells generate vascular endothelial cells (ECs)
  • Notch signaling pathway helps determine arterial program of both endothelial and smooth muscle cells (Stem Cells Int 2012;2012:805602)
  • See also Development 2011;138:4569, Int J Dev Biol 2011;55:419

Normal histology:
  • Vascular layers are outer tunica adventitia, intermediate tunica media and inner tunica intima; thickness depends on size and type of vessel
  • Tunica adventitia: longitudinally arranged collagen; layer is larger in veins than arteries
  • Tunica media: concentrically arranged smooth muscle whose diameter is altered by autonomic control; smooth muscle may secrete collagen, elastic fibers, elastic lamellae and proteoglycans; larger diameter in arteries than veins of similar size
  • Tunica intima inner endothelium and variable outer subendothelial connective tissue
  • Capillaries: no muscular layer or elastic lamella; endothelial layer is complete, with pericytes present but difficult to identify on H&E
  • Glomus cells: (a) modified smooth muscle cell with indistinct borders, pale cytoplasm, uniform nuclei; surround arterial segment of glomeriform arteriovenous anastomosis, which is richly innervated by autonomic nervous system fibers; or (b) peripheral chemoreceptor in carotid body and aortic body that detects hypoxia (Novartis Found Symp 2006;272:54); large, epithelioid cells with abundant cytoplasm and membrane bound, electron dense granules; richly supplied with nerve endings, see diagram below
  • Pericytes: relatively undifferentiated cell that regulates microvascular blood flow (Histol Histopathol 1991;6:269, Microvasc Res 2009;77:235)
  • References: University of Ottawa, Southern Illinois University, Victoria College

Aging related changes:
  • Normal vascular structure changes during life, with progressive arterial stiffness
  • Capillaries: basement membrane thickens with aging
Micro Images

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Artery #1: H&E

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#2: elastin

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#3: trichrome

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Arteriole


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Venous wall

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Pericytes

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Artery wall: blue arrow is tunica intima;
black bracket is tunica media;
green bracket is tunica adventitia

Positive Stains
Electron Microscopy Description
  • Endothelial cells: cells are jointed by tight, adherans or gap junctions; numerous pinocytotic vesicles, cytoplasmic microfilaments, microvilli, continuous basal lamina and Weibel-Palade bodies (membrane bound organelle which contains von Willebrand factor)
  • Capillary endothelium: surrounded by basement membrane which contains pericytes, in contrast to lymphatic endothelium which contains little basement membrane
Electron Microscopy Images

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Brain capillary with endothelial cells and pericyte

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Endothelial tight junction

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Pericytes