What do mast cells secrete during an injury?

Volkmann's canals occur in

Refer to the given figure and identify the correct characteristic features.
$(i)$ It is a type of loose connective tissue.
$(ii)$ It contains fibroblasts,macrophages,collagen fibres,and mast cells.
$(iii)$ The cells of this tissue are specialized to store fats.
$(iv)$ It forms the inner lining of blood vessels,stomach,and intestine.

Mast cells are found in

In vertebrates,where is sulfate found?

What is the function of the subcutaneous adipose tissue layer?