arteries are composed of three layers; tunica intima, tunica media, and tunica
innermost tunica intima consists of a squamous
endothelial layer lining a well-defined lumen. The endothelium
is difficult to preserve, and is therefore, not easily identifiable in these
sections. The endothelium sits on a basal lamina and a thick subendothelial
layer of loose connective tissue, smooth muscle, collagen and elastic
lamellae. No distinct border between the tunica intima and media exists.
middle tunica media is composed of a thick layer of
circumferential smooth muscle cells, pink collagen and red,
wavy, elastic lamellae. No fibroblasts are present in this layer.
outermost tunica adventitia consists of a thin connective
tissue layer containing fibroblasts, macrophages, and blood vessels
with little collagen and elastic lamellae.
that the elastic artery slide on the right is stained for elastic fibers.
The abundance of elastic fibers in the tunica media is prominent in this
slide. The aorta slide on the left is stained with H&E.
arteries, like elastic arteries, are composed of three layers; tunica intima,
tunica media, and tunica adventitia.
innermost tunica intima consists of a squamous endothelial
layer lining a well-defined lumen. The endothelium sits on a
basal lamina and thin subendothelial layer, which contains
fewer smooth muscle cells and less elastic tissue than elastic arteries.
A prominent internal elastic membrane separates the intima from the
media, and may appear wavy due to smooth muscle contraction.
middle tunica media is predominantly composed of circumferential
smooth muscle cells with little fine, wavy elastic material.
No fibroblasts are present in this layer.
outermost tunica adventitia is a thick layer of longitudinally
arranged collagen fibers bound by an external elastic membrane.
The adventitia blends in with the connective tissue of the surrounding adipose
tissue containing blood vessels.
section of liver on this slide demonstrates multiple muscular arteries. Scan
this slide for such arteries.
have the same, but often not as well-defined, layers as arteries. Because
of their thin walls, veins often appear to have irregular collapsed
lumena. Veins also frequently have valves.
tunica intima consists of a thin endothelial lining
with basal lamina and a thin layer of subendothelial tissue.
tunica media is relatively thin, containing smooth muscle
cells, collagen and fibroblasts. Veins have less elastic tissue
than arteries and the internal elastic membrane may be ill-defined or absent.
tunica adventitia is the thickest layer and is
composed of collagen and elastic fibres, as well as fibroblasts
and prominent bundles of longitudinally arranged smooth muscle.
section of liver on this slide demonstrates multiple veins. Scan this slide
for such structures.
heart wall is divided into three main layers; endocardium, myocardium and
innermost endocardium lines the atria and ventricles of
the heart. An inner endothelial layer overlies a subendothelial
connective tissue layer, a middle connective tissue layer containing
smooth muscle cells and an outer subendocardial layer containing
myocardium is composed of branching cardiomyocytes
with central nuclei, cross-striations and intercalated discs.
outer epicardium consists of a layer of mesothelial
cells on the outer surface of the heart overlying connective tissue
containing blood vessels and nerves. The epicardium is surrounded by adipose
of foam cells (macrophages filled with lipid droplets),
smooth muscle cells, and lymphocytes can be identified beneath the endothelial
layer of arteries.
central necrotic mass of lipid, cell debris and cholesterol
clefts lined by a fibrous cap of thick connective tissue
containing smooth muscle cells, macrophages, foam cells, lymphocytes, collagen
circumscribed area of ischemic coagulative necrosis
is seen within the heart wall. Cardiomyocytes appear wavy, have eosinophilic
cytoplasm and have lost their cross-striations and nuclei. Neutrophilic
infiltrate is seen initially, followed by lymphocytes and macrophages. Granulation
tissue will eventually replace the infarct with a fibrous (collagenous) scar.
Contraction bands may be identified peripherally in reperfused infarcts.
fibres are disrupted by interstitial infiltrate of lymphocytes and macrophages.
composed of platelets, fibrin, cell debris, and organisms are seen overly
an edematous and inflamed valve.