A 6-year-old boy was brought to the emergency room because of excruciating pain in the scrotum. The diagnosis of testicular torsion was made, but the testes were already necrotic and had to be surgically removed. This infarct was caused by
A. arterial thrombosis
B. arterial embolism
C. blockage of venous outflow
D. venous thrombosis
E. lymphatic obstruction
C
Torsion of the testes causes obstruction of the veins, which have thinner walls than the arteries. Back pressure from the venous end of the circulation is transmitted into the tissues and from there into the arteries, preventing them from supplying the oxygen carrying blood to the testes. Since no blood can enter the testes, the tissue undergoes ischemic necrosis. On cross-section examination the parenchyma of the necrotic testes is permeated with venous blood and appears dark bluish red.
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A) articular cartilage B) spongy bone C) periosteum D) red bone marrow
Which part is located in the inner ear?
A. cochlea B. auricle C. malleus D. stapes
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Fill in the blank(s) with the appropriate word(s).