24 [0-0]: [7-1]:H & E- Blood vessels consisting of veins (b) and arteries (c) progressively branch to form venules (d), arterioles (e) and capillaries (a). [7-2]:H & E- A whole mount of a large blood vessel showing elastic fibers within the blood vessel wall. [7-3]:H & E, Orcein- A medium size artery occurs with its companion vein which has folded over to provide two sections through the same vein. Compare the relative size of the tunica media and tunica adventitia in both artery and vein. The orcein stain has identified elastic fibers. Note the highly scalloped appearance of the internal elastic lamina of the artery and less scalloped appearance of the internal elastic lamina in the veins. [7-4]:Orcein-PIC, A medium size artery showing well defined tunica intima adjacent the internal elastic lamina, a well developed tunica media (brown) containing elastic fibers, and the tunica adventitia (green) continuous with the surrounding connective tissue. [7-5]:H & E, Orcein- This higher power view through a muscular artery shows the scalloped internal elastic lamina as well as prominent elastic fibers within the tunica media and an abundance of elastic fibers within the tunica adventitia. [7-6]:H & E- This medium sized vein shows vasa vasorum (arrows) within the tunica adventitia. [7-7]:TEM 9-1, This section through the wall of a blood vessel shows from the lumen (1) outwards, the nucleus of an endothelial cell (2), a centriole (3) and caveolae (4) within endothelial cells, caveolae within a smooth muscle cell (5), cytoskeletal filaments (6), the basal lamina (7) and the nucleus of a smooth muscle cell (8). [7-8]:H & E- Arterioles (a, c), venules (b) and capillaries (d) are abundant within the dermis. [7-9]:H & E- This longitudinal section through an arteriole (arrows) shows the squamous endothelial cells of the tunica intima adjacent to smooth muscle cells of the tunica media. the tunica adventitia merges with the surrounding connective tissue. [7-10]:TEM 9-3. This arteriole exhibits an erythrocyte (1), endothelial cells (2), internal elastic lamina (3), the nucleus (5) of smooth muscle cells (4) of the tunica media, and connective tissue of the tunica adventitia (6). [7-11]:H & E- Capillaries form an anastomosing plexus within the alveolar wall of the lung. [7-12]:H & E- the cross section of a capillary (arrows) is lined by a single endothelial cell. Name the leukocyte that fills the lumen of this capillary. Answer- Monocyte. [7-13]:TEM 9-2, The lumen (2) of this capillary is filled with a erythrocyte (1). The endothelial cells (3) lining the capillary contain caveolae (4). A distinct basal lamina (5) bounds the capillary. [7-14]:TEM 10-5, This capillary within the lung is filled with an erythrocyte (1). The endothelial cells (2) lining the capillary are bounded by a basement membrane (3). An adjacent smooth muscle cell (4) and the endothelial cells contain caveolae (6). Collagen fibrils (5), a zonula occludens (7) and the lumen of the lung alveolus (8) can also be observed. What type of capillary is shown in this TEM? Answer- Continuous capillary. [7-15]:TEM 6-6, A continuous capillary lined by simple squamous endothelium. 1. Capillary lumen; 2. Endothelial cell nucleus; 3. Endothelial cell junction; 4. Basement membrane; 5. Pericyte; 6. Astrocyte processes. [7-16]:SEM 15-7, Sinusoids (S) within the liver exhibit large fenestrations (X) that form openings within the endothelial lining of the vessels. [7-17]:H & E- The aorta consists of a typically thin tunica intima (a) and a very thick tunica media (b). The boundary (dotted lines) between the tunica media and tunica adventitia (c) is distinct. [7-18]:Orcein- The aorta is a typical example of an elastic artery which contains abundant elastic laminae within the tunica media. [7-19]:H & E- Large veins such as the vena cava contain a thin tunica media (a) whereas the tunica adventitia (line) contains longitudinal bundles of smooth muscle (arrows). [7-20]:H & E- In this section of the vena cava the thin tunica media (line) can be distinguished from the tunica adventitia containing vasa vasorum (arrows). [7-21]:H & E- In this longitudinal section of the junction between the heart and the aorta the aortic valve can be seen projecting from the left ventricle into the aorta. [7-22]:H & E- The atrioventricular valve (d) joins at its base (c) to the cardiac skeleton. Endocardium (f), a coronary artery (a) and coronary vein (b) are also identified. Note the difference in thickness of the myocardium between the atrium and the ventricle. [7-23]:H & E- Purkinje fibers in longitudinal (b) and oblique (a) section occur within the subendocardial layers of the heart and function as an impulse conducting system for contraction of the myocardium.