Arrows point to Vasa Vasorum
Arteriole - H&E
Example - Superior Vena Cava
Sinusoidal (discontinuous) capillary
Large irregular lumen. Discontinuous basal lamina. Found in Bone marrow, liver, spleen (sites of fluid & cell migration in & out of BV).
Elastic (conducting) artery. 40-70 fenestrated elastic sheets. Example - aorta.
Fenestrated (type II) Capillary. Fenestrations, complete basal lamina. Found in endocrine organs, GI tract, kidney.
- Cardiac Valves - Specializations of the endocardium (Tunica Intima).
- Extensions of fibroelastic tissue deep to endothelium.
Draw blood from an elastic artery and branch into "resistance vessels" including small arteries and arterioles. They contain layers of smooth muscle.
muscular arteries and medium veins - often found next to each other.
Internal Elastic Lamina (IEL). Permits diffusinof nutrients and waste between lumen, cells in tunica intima, and the cellsin inner half of tunica media.
Arrows point to Weibel-Palade bodies
Core of subendothelial CT covered by endothelium
Continuous (type I) Capillary - TEM
Muscular (distributing) artert. 5-40 layers of smooth muscle. Example - internal thoracic artery
Tunica Media. Smooth muscle, contractile and/or secretory, coordinate via gap junctions.
External Elastic Lamina (EEL)
Separates tunica media from TA, secreted by smooth muscle cells of the tunica media.
Medium vein - example - cephalic vein
Precapillary sphincter - Red circle and arrows
Atherosclerotic Plaque - Within the tunica intima.
Continuous (type I) Capilarries - LM
Modified cardiac muscle fibers, located in subendocardial, (not epithelial). Large pale-looking (“moth-eaten) cells.
muscular walls (usually only one to two layers ofsmooth muscle), the primary site of vascular resistance.
The greatest change in blood pressure and velocity of blood flow occurs at the transition of arterioles to capillaries.
Transmission electron micrograph of a microvessel, showing pericytes characteristically lining the outer surface of endothelial cells, which encircle an erythrocyte (E).