Xylem vesseles

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Assiut UniversityFaculty of scienceBotany department : 

Assiut UniversityFaculty of scienceBotany department Under supervision of: Prof-Dr Mo’men El Zarieh By : Mohamed Tag eldin Mohamed

Xylem vessels : 

Xylem vessels Development The origin of the xylem vessels is the procambial meristem and the cells of divide to give a chain of mother cells arranged as end to end cells then the end walls and cells contents are disintegrated to form a long tube then the walls are be thicken by lignin at this state we call it primary xylem then the diameter and thickness of walls increase to arrive the top of them at the secondary xylem .

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Structure The main component that built the vessels is the lignin and it has a regular shape on the walls like : Spiral and annular presents at the protoxylem Reticulate and pitted presents at the metaxylem and secondary xylem

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The side walls of vessels have a lot of pits the type of them , their number and their arrangement depend on the neighbor cell type If it was the neighbor cell vessel the number of them will be huge but if it was the neighbor fiber they will be a few

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For the end walls when they taper perforation presents and this happens at three steps Firstly the perforation begins to appear at such a area at the wall that called the perforation plate

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Secondly perforation occurs but there is some remains of the perforation plat still there that called perforation rim At last the perforation completes and the remaining wall stripes called perforation bars

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But the perforations has also types but their types depend on the wall and the plant and their types are : Simple perforation: it have one open and presents at the transverse walls

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Multiple perforation: it have more than one open Scalariform perforation : like the multiple perforation and presents the oblique walls

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Function Vessels have two functions and their structure helps it to perform these functions and we will explain this Transporting water and ions all over the plant and it’s tubular shape ,lignin and their pits help it to perform this function Supporting and holding the plant and it’s solid flexible structure helps to perform this function

Differences between vessels and Tracheids : 

Differences between vessels and Tracheids

Thanks for all of you : 

Thanks for all of you

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