HISTO BLOCK II

• A endothelial cells
• B tunica intima
• C tunica media
• D tunica aventitia

• blue-tunica intima
• yellow-tunica aventitia
• red- vaso vasorum

• blue-tunica intima
• yellow-tunica aventitia
• red-vaso vasorum

• A-internal elastic membrane
• B-smooth muscle
• C-external elastic lamella
• D-elastic fibers
• E-collagen fibers

• A-aventitia
• B-internal elastic lamina
• C-tunica media

tunica interna thickness varies with age, may be very thin in kids and thick in adults

• A-INTERNAL ELASTIC LAMINA
• B- SMOOTH MUSCLE

• Red…nuceli of smooth muscle
• Yellow…subendothelial connective tissue
• Green…elastic membrane

mesenteric artery stained for elastin

• A-endothelial cells
• B-small blood vessels

Small arteries may have up to 8 layers of smooth muscle in tunica media and they may have an internal elastic membrane

• Arrows black-endothelial cells in contact with blood
• Arrow Yellow-smooth muscle later
• A-arteriole 
• B-venule

• black arrows-endothelial cells
• red-arrow-nuclei in smooth muscle cell
• A-RBC
• SM-smooth muscle
• F-fibroblasts in tunica aventitia

• Blood cells RED
• Endothelia cells YELLOw
• Precapillary spinchter…BLUE