Sclerenchyma-1

Sclerenchyma-1
	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. The pink objects are amyloplasts stained via PAS. Viewed with Phase optics, color by Deluxe!
Sclereid under construction. Note the similarity in shape to the Parenchyma cell above. However, note the difference in wall thickness. The new wall is called Secondary and is deposited after the cell has ceased enlargement. Parenchyma cells can eventually develop into Sclerenchyma cells. However, this is not usually the case. The distinguishing features of Sclerenchyma are the presence of a thick Secondary Wall which has highly organized cellulose microfibrils, and usually contains Lignin. Viewed with Phase optics.
	SEM Photo of a cell like the one above. note the lamella appearance of the wall (lower left). The largest organelle is the Nucleus.
	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 (idioblast) or in small clusters. They are usually isodiametric although some can be very long. They have prominent Pits & are generally lignified. Find these features in the high magnification image!
	*A Sclereid from Begonia. Note the pits and the wall laminations.*
	The term Brachysclereid is used for isodiametric sclereids like this from pear. The secondary wall almost occludes the cell. It is traversed by large branching (ramified) pits.The red color is due to Lignin (stained with Phloroglucinol).
	These are clusters of Brachysclereids from pear flesh.
	Closer view of the above. Compare the individual cells with the solitary one above.
	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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