Mast cells of connective tissue contain

Options

A. heparin and histamine
B. heparin and calcitonin
C. serotonin and melanin
D. vasopressin and relaxin

Answer

**Step-by-Step Solution:**

1. **Understanding Mast Cells**: Mast cells are a type of connective tissue cell that play a crucial role in the immune response. They are known for their large size and granular cytoplasm.

2. **Identifying the Contents of Mast Cells**: The primary substances found in mast cells are histamine and heparin. Histamine is involved in inflammatory responses and acts as a vasodilator, while heparin is an anticoagulant that helps prevent blood clotting.

3. **Evaluating the Options**:
- **Option A**: Heparin and histamine - This is correct as both are found in mast cells.
- **Option B**: Heparin and calcitonin - Incorrect, as calcitonin is not found in mast cells; it is produced by the thyroid gland.
- **Option C**: Serotonin and melanin - Incorrect, as melanin is produced by melanocytes in the epidermis, not mast cells.
- **Option D**: Vasopressin and relaxin - Incorrect, as vasopressin is secreted by the posterior pituitary gland and relaxin is produced by the corpus luteum and placenta.

4. **Conclusion**: After evaluating all the options, the only correct answer is that mast cells of connective tissue contain heparin and histamine.

**Final Answer**: Mast cells of connective tissue contain heparin and histamine.

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