Heparin, Serotonin, and histamine are secreted by
oesophagus
In areolar tissue, the cells found are fibroblasts, mast cells, and macrophages which are held in a loose matrix. Each cell has got a specific function of its own, which are
Mast cells secrete Heparin ( anticoagulant )
Histamine ( Vasodilator) which lowers BP and
Serotonin ( Vasoconstrictor) which increases BP.