Question

vasoactive mediator in granules of mast cells and is the primary cause of allergies and anaphylactic shock... histamine clistema chyli mast cell

Explanation:

Histamine is a vasoactive mediator stored in granules of mast cells and is well - known as the primary cause of allergies and anaphylactic shock. Cisterna chyli is a part of the lymphatic system and mast cell is the cell type that contains the histamine, not the mediator itself.

Answer:

Histamine