Cell structures

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Cell structures

• 1- Types of cells ( contd )
• 2-Cell contents.
• 3- Pollen grains.

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Types of cells

• Fibres
• Tissue composed of spindle-shaped or elongated
  cells with pointed ends, when thick-walled
  (lignified), they are known as fibres.
• Example
• Cinchona Fibres.
• Senna Fibres.

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Senna leaves
Cinchona Bark
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Under Light Microscope
Cinchona Fibres
Prisms of calcium oxalate
Crystal Sheath in Senna
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2- Cell Content

• Calcium oxalate
• It is an end product of cell metabolism as a
  result of the reaction of calcium and oxalic
  acid.
• Calcium oxalate precipitates in cells in the form
  of crystals of different shapes sizes .
• Types of calcium oxalate crystals
• 1-Prisms (Senna).
• 2-Clusters (Rhubarb, Datura stramonium).
• 3-Microsphenoidal sandy crystals (Idioblasts)
  e.g.Belladonna

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Calcium oxalate clusters (crystal layer) in
Datura stramonium
Calcium oxalate clusters in Rhubarb
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Microsphenoidal sandy crystals of calcium
oxalate (Idioblasts ) Atropa belladonna
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3-Pollen Grains

• They are very minute particles vary in shape and
  size and consists of 2 walls
• Outer wall (exine) contains germinal pores.
• Inner walls ( intine).

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Lavendula officinalis
Matricaria chamomilla
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The shape of pollen grain may be
1- Hexagonal
2- Spiny
Spiny pollen grain (Chamomile Pyrethrum)
Hexagonal pollen grain (Lavander)
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