Q. Balloon-like structure formed by adjacent parenchyma cells into xylem vessels through pits are

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Solution:

Tyloses are the balloon-like structures that block the lumen vessels. These are parenchyma cells (axial and ray parenchyma of xylem) associated with vessels that are connected through pits. These parenchymas develop into balloon-like protrusions in the vessels and finally becomes dead and lignified that results in the blockage of vessels.
A tylosis contains a nucleus with a certain amount of cytoplasm coming from the living cell. Starch, resin, and other matters may also be pre­sent in it. The initial thin walls of tyloses may undergo lignification later leading to the forma­tion of sclereids. A single tylosis may divide and form multiple structures.
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