MICROANATOMY

Detailed explanation-1: -A mast cell is derived from the myeloid stem cell. It is a part of the immune and neuroimmune systems and contains many granules rich in histamine and heparin. Mast cells contain electron-dense cytoplasmic granules and stain metachromatically with selected basic dyes. Hence, option D is correct.

Detailed explanation-2: -In addition, mast cells release proteases and heparin which release pro-angiogenic factors that bind to heparin. Histamine, released by mast cells, induces permeability of the microvasculature that also induces angiogenesis. There is also evidence of mast cells enhancing angiogenesis in tumor growth (20).

Detailed explanation-3: -Mast cell granules are particularly rich in proteases. These proteases are the major proteins present in mast cells; representing up to 50% of the total protein content of the granule.