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The Circulatory System

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Slide 1: This plastic embedded section shows several blood capillaries and a small nerve. The tissue was fixed by perfusion so the arteriole present in the field is maximally open. Scattered red cells are extravascular, probably from blood vessels broken during dissection. In routine paraffin preparations, capillaries are very often collapsed and difficult to find in their natural abundance.  

Slide 2: TEM of a small fenestrated capillary (guinea pig kidney cortex). Note the large nucleus, sparse organelles and fenestrae. It is apparent that here the entire capillary is one cell. Note the delicate basal lamina. Adjacent cells are epithelial cells with basal infoldings.  

Slide 3: TEM of the alveolar wall of the lung. Capillary (find the endothelial cell nucleus), CT and smooth muscle in interstitium. If you are reviewing this after you have studied the respiratory system, find the Type I (no nucleus) and Type II pneumocytes.  

Slide 4: A large capillary in adipose tissue is sectioned longitudinally. It contains a rouleaux of rbc's.  

Slide 5: A small arteriole, 3 venules (from a large one which is almost a vein to post-capillary in size) and a capillary (not sectioned through its nucleus). Also find adipose cells and smooth muscle (oblique sect). Plastic embedded section.  

Slide 6: Arteriole, venule and lymphatic from perfused tissue. The lymphatic has an extremely thin wall (mostly just endothelium), is quite large, and like the arteriole, devoid of content. The venule contains 2 rbcs. The adjacent tissue is pancreas. Find the one capillary (with its nucleus in the section) in among the pancreatic tissue. Toluidine-blue and acid fuchsin, plastic embedded section.  

Slide 7: A small arteriole (distinguishable by the circumferential orientation of smooth muscle cell nuclei) runs diagonally across the field. From the mesentary whole mount microscope slide (#100 of student set). Giemsa stain.  

Slide 8: An arteriole sectioned longitudinally and obliquely. Plastic embedded section.  

Slide 9: Muscular artery x.s. Note the multiple layers of smooth muscle cells in the media.  

Slide 10: This is a small muscular artery, plastic embedded section. It is slightly obliquely sectioned and shows the smooth muscle cells and internal elastic membrane very distinctly.  

Slide 11: TEM of vessel similar in size to that shown previously. There are approximately 5 layers of smooth muscle and some of the smooth muscle cells are contracted (note the twisted nucleus). Thus, the endothelium appears thicker than it actually is. The internal elastic membrane is seen as an interrupted layer just beneath the epithelium. Collagen, although present near muscle cells, is not clearly banded. The black strips to the left of the field are folds in the EM section.  

Slide 12: Small muscular artery or large arteriole and small vein, low power. This slide is faded and the artery is sectioned obliquely in part.  

Slide 13: Muscular artery (brachial) stained for elastic tissue. Note the internal elastic membrane and that there is more elastic tissue in the adventitia than tunica media. Note the arteriole (about 4 layers of smooth muscle) in the connective tissue external to the adventitia.  

Slide 14: Muscular artery and accompaying vein. Elastic stain. Again, note the difference in the distribution of the elastic tissue.  

Slide 15: Aorta, low power. Plastic embedded section. This vessel was not agonally contracted. The internal elastic membrane is not easily discerned. Monkey.  

Slide 16: Vena cava, low power. Plastic embedded section. Monkey.  

Slide 17: Inferior vena cava. Elastic stain. Elastic = dark brown, smooth muscle = medium brown, CT = light brown. Note smooth muscle in intima, circular smooth muscle in media and longitudinal smooth muscle in adventitia. Human.  

Slide 18: Obliquely sectioned vein (contains rbc) and adjacent lymphatic (contains precipitated proteins and no rbc).  

Slide 19: 3 lymphatic vessels (no red cells just proteins & lymphocytes), muscular arteries (small amount of blood and rbs'c) and a medium vein (a lot of blood with rbc's).  

Slide 20: A lymphatic vessel that branches and has a valve. Mesentary whole mount. There is also a vein (so thin walled that you see the rbc's in it) in the image. Purple, out of focus "sploches", are mast cells (student microscope slide #100). Giemsa stain.  

Slide 21: Find the large distended lymphatic containing 2 lymphocytes. Also locate 4 arterioles and a venule, gut submucosa, plastic embedded section.  

Slide 22: Lymphatic l.s., with a valve in wall of gall bladder (not human). Note the lymph and lymphocytes.  

Slide 23: Part of a cross section of a lymphatic. Note lymph and lymphocytes as well as the very thin wall.  

Slide 24: Low power section near atrioventricular junction (at c). d = A-V valve, f = endocardium. b = coronary vein. Note the thick ventricular muscle.  

Slide 25: Ventricular muscle inserting into the region of the cardiac "skeleton" at low power  

Slide 26: Endocardium. Human cardiac muscle is hard to identify as such.  

Slide 27: Endocardium (dark blood in ventricular cavity) and Purkinje fibers l.s.  

Slide 28: Endocardium, note the small amount of connective tissue, and just beneath the Purkinje fibers sectioned almost longitudinally. Cardiac muscle is at the bottom of the field.  

Slide 29: Atherosclerotic human coronary artery. Question: Can you find where the lumen was? (Ans: the small"slit" at the bottom containing some blood, i.e., the mouth of the "sad face"!).

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