Circulatory system 

The picture " " can link to it's
corresponding histological photograph. 

The picture " " can link to it's
corresponding histological drawing.

   A. Heart, NE-2-j, l 

Special staining in NE-2-j: muscle fibers are deep gray, Purkinje fibers are light gray


»»  visceral pericardium, mesothelium
»»  loose connective tissue
»»  fat cells
»»  small arteries and small veins, coronary vessels
»»  autonomic nerves


»»  bundles of cardiac muscle fibers (cs, ls, os)
»»  blood vessels located in connective tissue between muscle fibers
»»  cardiac muscle fibers; recall Exp. 3
»»  Centrally located nucleus
»»  Juxtanuclear sarcoplasm
»»  branches of muscle fibers
»»  intercalated discs


»»  endothelium
»»  subendothelial (subendocardial) connective tissue
»»  Purkinje fibers, specialized cardiac muscle fibers, NE-2-l ; larger in size, more sarcoplasm and sparser myofibrils than those of cardiac muscle fibers

   B. Valves 
aortic, human, l.s.: NG-2-b; 

mitral, human: NG-2-c

»»  endothelium
»»  lamina fibrosa: dense connective tissue
»»  chordae teninae (only in ventricle)
»»  papillary muscle
(only in ventricle)

   C. Blood vessels

a. Large artery (Elastic artery)
G-2-d, HE or G-2-f, HE or Orcein 

NG-2-a, Van Gieson stain

Elastic membranes are stained brown in slide G-2-f, orcein stain, or are deep purple in NG-2-a

»»  tunica intima
@internal elastic membrane, not very clear
»»  tunica media
@unstained concentric elastic membrane (lamellae)
@nuclei of circularity arranged smooth muscle fibers
»»  tunica adventitia
@connective tissue
@irregularly arranged collagenous fibers
@vasa vasorum

b. Vena cava 
(NG-2-i, cs, Van Gieson)

elastic fibers can be seen in tunica media and adventitia

»»  tunica intima, very thin
»»  tunica media, poorly developed than in aorta
»»  tunica adventitia
@well developed
@numerous bundles of longitudinal smooth muscle fibers
@collagenous fiber bundle
@vasa vasorum

c. Medium-sized artery & vein 
NG-1-b, cs, human
NG-1-c, cs, HE, fetus

external elastic membrane may be found located between tunica media & adventitia

»»  tunica intima
internal elastic membrane
poorly developed in veins
»»  tunica media
@well developed in arteries (several layers of smooth @muscles) thin in vein
»»  tunica adventitia
@poorly developed in artery
@well developed in vein

d. Small artery or arteriole
The thickness of tunica media varies with diameter of vessels. There are 2-3 layered smooth muscle cells in tunica media of small arteries. The smallest artery or called arterioles are composed only one layer of smooth muscle fiber in tunica media. These types of arteries, arterioles and accompanying venules are often observed in other tissue slides. (eg. Nf-1-b sympathetic ganglion)

d. Capillaries,
eg. in cardiac tissue, NE-2-j
eg. T-7-d cerebellum; T-4-c cerebrum