Question 19

Question:

While skipping rope, a 7 year old girl falls and scrapes her knee on the pavement. Four days later, she picks at a hard, reddish-brown raised formation at the site of the injury which reveals soft, moist pink tissue. Which is the predominant cell type found in this underlying tissue?

Correct Answer: B.  Fibroblast

Granulation tissue forms within 3-5 days after severe or persistent injury has occurred. It is characterized by proliferation of fibroblasts and new capillaries that will form the scaffolding for scar formation. Epithelioid macrophages are large and squamous-cell like, found in chronic inflammation, such as in tuberculosis or sarcoidosis. Neutrophils are the predominant leukocytes found in acute inflammation, usually within the first 24 hours of injury. Platelets create a “plug” at the site of bleeding on which a fibrin clot forms a scab within the first few hours of injury. Mast cells release histamine during acute inflammation, which causes vasodilation and increased vascular permeability.