Question

the balloon shaped stucture called tyloses

Answer 1

Tyloses -

Bladder like ingrowth of parenchyma cells into lumen of vessels

- wherein

Tylose blocks the conduction of water. In gymnosperms, tylosoids are formed in place of tyloses.

Answer 2

are extensions of xylem parenchyma cells into vessels 

Tyloses are ballon like parenchymatous ingrowth in vessels adjacent to xylem vessels and tracheids of the heartwood. They inhibit transportation of water & minerals in xylem.