Histology of cardiovascular system : Blood Vessels

BLOOD VESSEL

Classification of blood vessels based on the structure

  1. Arteries
    • Elastic, Large or conducting arteriesConduct blood away from the heart.
      Micro-photograph of Artery VS Vein under Light Microscope magnification 4x

      Micro-photograph of Artery VS Vein under Light Microscope magnification 4x

      Important in maintaining constant pressure in arterial system

    • Muscular arteries or medium sized arteriesThey distribute the blood to the tissues
  2. Veins
    • Large veins
    • Medium sized veins

Wall of the blood vessels

Typically having three concentric layers.

  1. Tunica intima – innermost layer
  2. Tunica media – middle layer
  3. Tunica adventitia (externa) – outermost layer


Histology of elastic arteries

  • Tunica intima – thicker than in muscular arteries
    . Endothelium rests on thin basal lamina
    . Internal elastic lamina may be present between intima & media, but hard to distinguish because of abundant elastin fibres in media.
  • Tunica media – contains abundant elastin as concentrically arranged interspersed with smooth muscle fibres.
  • Tunica adventitia – thin relative to vessel diameter, contains elastic & type I collagen fibres
    ,Vasa vasora are seen.
  • e.g. – aorta

Histology of Muscular or distributing arteries

  • Tunica intima – Contains typical endothelium & subendothelial connective tissue.
    Prominent internal elastic lamina appears as wavy, refractile line between intima & media.
  • Tunica media – Thick , Up to 40 layers of smooth muscle fibers.
    Collagen, elastic fibres & proteoglycan vary.
  • Tunica adventitia – Relatively thin & contains mostly collagen fibres

Histology of Large veins


  • Tunica intima
    – Well developed & include thick layer of subendothelial connective tissue.
    Extensions of intima protrude into lumens of large veins as valves.
  • Tunica media – several layers of smooth muscle cells & abundant reticular & collagen fibres. Elastin is sparse.
  • Tunica adventitia – best developed in large veins contains abundant collagen & longitudinal bundles of smooth muscle that strengthen vessel to prevent distension.
  • Eg.- Vena cava

Histology of Small & medium sized veins

Narrower than large veins & have thin walls.

  • Tunica intima -Typical endothelium, less subendothelial tissue. fewer valves than large veins, no internal elastic lamina.
  • Tunica media -Thin relative to vessel diameter. Few elastic fibres.
  • Tunica adventitia – Relatively thick, but unlike large veins contains little of any muscle.
    Mostly collagen.
  • e.g.– saphenous, hepatic, portal etc.

Micro-Photograph of Blood Vessels

Below are blood vessels at various magnification.

Micro-photograph of Muscular Artery under Light Microscope magnification 4x

Micro-photograph of Muscular Artery under Light Microscope magnification 4x

Micro-photograph of Muscular Artery under Light Microscope magnification 10x

Micro-photograph of Muscular Artery under Light Microscope magnification 10x

Micro-photograph of Aorta - Large Elastic Artery under Light Microscope magnification 10x

Micro-photograph of Aorta – Large Elastic Artery under Light Microscope magnification 10x

Micro-photograph of Muscular Artery under Light microscope magnification 10X

Micro-photograph of Muscular Artery under Light microscope magnification 10X

Micro-photograph of Artery VS Vein under Light Microscope magnification 4x

Micro-photograph of Artery VS Vein under Light Microscope magnification 4x

Micro-photograph of Vena Cava - Large Vein under Light Microscope magnification 4x

Micro-photograph of Vena Cava – Large Vein under Light Microscope magnification 4x

Micro-photograph of Large Vein under Light Microscope magnification 10x

Micro-photograph of Large Vein under Light Microscope magnification 10x

Micro-photograph of Large Vein - Tunica Intima under Light Microscope magnification 40x

Micro-photograph of Large Vein – Tunica Intima under Light Microscope magnification 40x

Micro-photograph of Large Vein - Tunica Adventitia under Light Microscope magnification 40x

Micro-photograph of Large Vein – Tunica Adventitia under Light Microscope magnification 40x

Micro-photograph of Large Vein - Tunica Media (top) and Adventitia (below) under Light Microscope magnification 40x

Micro-photograph of Large Vein – Tunica Media (top) and Adventitia (below) under Light Microscope magnification 40x

Adapted from: http://myaimst.net/mbbsb12/photo/histo/yr2histo/bloodvessels.html
Micro-photograph taken at AIMST University Multi Disciplinary Laboratory during Histology class, using Canon A40 camera over light microscope.


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