Sclerenchyma-1

Sclerenchyma-1 Scler means Hard. Sclerenchyma cells have Thick, Highly Organized, Lignified Cell Walls which makes them hard & strong.
	Cellulose Fibril orientation is usually random in cells which are still enlarging. This is easy to imagine if you think of a baloon with lines painted on it. Their orientation will change as the baloon fills with air.
	Secondary Walls are produced AFTER enlargement has ceased. These are highly organized, especially in Sclerenchyma. The pitch of the secondary walls depends on the orientation of Microtubules in the cytoplasm. Alternating layers have an opposing pitch. This produces a laminated wall that is extremely strong.
	Two unsuspecting Parenchyma cells on a stroll in the park. How are they to know that they will soon be transmogrified into Sclerenchyma cells. Note the overall cell shape and wall thickness. Nuclei are prominent in the thin peripheral cytoplasm.
	Sclereid under construction. Note the similarity in shape to the Parenchyma cells above. However, note the difference in wall thickness. The new wall is called Secondary and is deposited after the cell has ceased enlargement. The distinguishing features of Sclerenchyma are the presence of a Thick Secondary Wall which is highly organized, and usually contains Lignin.
	A large Sclereid. Note the laminated, thick secondary walls. The red stain indicates the presence of Lignin. There are two types of Sclerenchyma. Sclereids occur alone or in small clusters. They are usually isodiametric although some can be elongated. They have prominent Pits & are generally lignified.
	These are clusters of Stone Cells (Brachysclereids) from pear fruit. The gritty sensation you get when eating peas is due to these Sclereids.
	The secondary wall almost occludes the cell. It is traversed by large branching pits. The red color is due to Lignin.
	*Large Sclereid from the leaf of Podocarpus.* Note the wall laminations and the Pits around 3 & 5 o'clock. Viewed with polarized light.
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