<h2><strong>Sclerenchyma Tissue</strong></h2>
<p>Sclerenchyma is a simple, permanent tissue. It is the supporting tissue in plants, making the plants hard and stiff. Two types of sclerenchyma cells exist: <em>fibres</em> and <em>sclereids</em>.</p>
<p><em>Sclerenchyma fibres</em> are long and narrow and have thick lignified cell walls. They provide mechanical strength to the plant and allow for the conduction of water.</p>
<p><em>Sclereids</em> are specialised sclerenchyma cells with with thickened, highly lignified walls with pits running through the walls. They support the soft <a data-lesson="complex-tissue-structure" data-subject="biology" data-tutorial="introducing-animal-diversity" href="https://app.ulearngo.com/biology/introducing-animal-diversity/complex-tissue-structure">tissues</a> of pears and guavas and are found in the shells of some nuts.</p>
<table>
<tbody>
<tr>
<td colspan="3">Sclerenchyma</td>
</tr>
<tr>
<td><b>Diagram</b></td>
<td colspan="2"><b>Micrograph</b></td>
</tr>
<tr>
<td>
<div class="wp-caption alignnone" style="width: 210px"><img alt="Image" height="235" src="https://data.ulearngo.com/assets/e6599540-e768-4735-8eda-9c68e4803194" width="210"/><p class="wp-caption-text">Sclerenchyma tissue provides support in plants.</p></div>
</td>
<td>
<div class="wp-caption alignnone" style="width: 210px"><img alt="Image" height="157" src="https://data.ulearngo.com/assets/3ee97db8-42c0-4c2c-8a12-3539b4b40fb6" width="210"/><p class="wp-caption-text">Cross-section of sclerenchyma fibres.</p></div>
</td>
<td>
<div class="wp-caption alignnone" style="width: 210px"><img alt="Image" height="158" src="https://data.ulearngo.com/assets/0ed200b0-66e1-4466-843d-ce67d730a884" width="210"/><p class="wp-caption-text">Sclereid.</p></div>
</td>
</tr>
</tbody>
</table>
<table>
<tbody>
<tr>
<td colspan="2">Sclerenchyma</td>
</tr>
<tr>
<td><em>Structure</em></td>
<td><em>Function</em></td>
</tr>
<tr>
<td>Cells are dead and have lignified secondary cell walls.</td>
<td>This provides mechanical strength and structural support. The lignin provides a 'wire-like' strength to prevent from tearing too easily.</td>
</tr>
<tr>
<td>Sclereids have strong walls which fill nearly the entire <a data-lesson="lung-volumes-and-capacities" data-subject="biology" data-tutorial="respiratory-system" href="https://app.ulearngo.com/biology/respiratory-system/lung-volumes-and-capacities">volume</a> of the cell.</td>
<td>Provide the hardness of <a data-lesson="development-of-fruit-and-fruit-types" data-subject="biology" data-tutorial="plant-reproduction" href="https://app.ulearngo.com/biology/plant-reproduction/development-of-fruit-and-fruit-types">fruits</a> like pears. These structures are used to protect other cells.</td>
</tr>
</tbody>
</table>
<p>Sclerenchyma tissues are important components in fabrics such as flax, jute and hemp. Fibres are important components of ropes and mattresses because of their ability to withstand high loads. Fibres found in jute are useful in processing textiles, given that their principal <a data-lesson="cell-wall" data-subject="biology" data-tutorial="introducing-the-cell" href="https://app.ulearngo.com/biology/introducing-the-cell/cell-wall">cell wall</a> component is cellulose. Other important sources of fibres are grasses, sisal and agaves. Sclereid tissues are the important components of fruits such as cherries, plums or pears.</p>
<div class="ns-tutorial">
<div class="ns-school-defn2">
<h3>Fact:</h3>
<p>A useful way to remember the difference between collenchyma and sclerenchyma is to remember the 3 Cs pertaining to collenchyma: thickened at <em>c</em>orners, contain <em>c</em>ellulose, and named <em>c</em>ollenchyma.</p>
</div>
</div>
<div>
<div class="ns-school-emp">
<h2>Investigation: <strong>Observing Sclerenchyma in Pears</strong></h2>
<div class="ns-school-defn">
<div>
<h3><b>Aim</b></h3>
<p>To observe sclerenchyma stone cells (sclereids) in pears</p>
<h3><b>Materials</b></h3>
<div>
<ul>
<li>soft, ripe pear</li>
<li>microscopes, <a data-lesson="using-a-microscope" data-subject="biology" data-tutorial="introducing-the-cell" href="https://app.ulearngo.com/biology/introducing-the-cell/using-a-microscope">microscope</a> slides and cover slips</li>
<li>iodine solution</li>
<li>dissecting needles or forceps</li>
</ul>
</div>
<h3><b>Instructions</b></h3>
<div>
<ol>
<li>Use the forceps or needle to lift a small piece of soft pear tissue onto your microscope slide.</li>
<li>Add a drop of iodine solution.</li>
<li>Mash the tissue slightly to separate the cells.</li>
<li>Cover with a cover slip and observe under low power. You should focus on the groups of dark "stones" that appear amongst the rounded <a data-lesson="parenchyma-tissue" data-subject="biology" data-tutorial="plant-and-animal-tissues" href="https://app.ulearngo.com/biology/plant-and-animal-tissues/parenchyma-tissue">parenchyma cells</a> of the pear. Try to find one or two stone cells or sclereids that are separate from the rest.</li>
<li>Enlarge a good specimen (or focus on the edge of a group where one cells sticks out) and adjust the lighting.</li>
<li>Look carefully while you focus up and down to see the long, narrow PITS running through the extremely thick walls of these cells.</li>
<li>These "stone cells" are called sclereids. They are a modified form of sclerenchyma found in pears, guavas and the shells of nuts for extra support.</li>
<li>Also observe the large round cells around the sclereids.</li>
</ol>
</div>
<h3><b>Questions</b></h3>
<div>
<ol>
<li>Do you see <a data-lesson="cytoplasm" data-subject="biology" data-tutorial="introducing-the-cell" href="https://app.ulearngo.com/biology/introducing-the-cell/cytoplasm">cytoplasm</a> inside the stone cells? Are they living or dead cells?</li>
<li>What tissue type do the large round cells around the sclereids belong to</li>
</ol>
</div>
</div>
</div>
</div>
</div>
<div>
<div class="ns-school-emp">
<h2>Investigation: <strong>To Investigate Sclerenchyma Fibres</strong></h2>
<div class="ns-school-defn">
<h3><b>Aim</b></h3>
<p>To see sclerenchyma fibres in tissue paper</p>
<h3><b>Materials</b></h3>
<ul>
<li>cheap toilet paper (single ply)</li>
<li>iodine solution or water</li>
<li>microscopes and slides</li>
</ul>
<h3><b>Instructions</b></h3>
<div>
<ol>
<li>Tear a tiny piece of toilet paper off the sample and mount it in <a data-lesson="water-and-life-2" data-subject="biology" data-tutorial="biology-foundations" href="https://app.ulearngo.com/biology/biology-foundations/water-and-life-2">water</a> or iodine solution.</li>
<li>Place on a cover slip and examine under the microscope on low power.</li>
<li>Focus on the torn edge of the paper and observe the long sclerenchyma fibres.</li>
<li>Observe on high power.</li>
</ol>
</div>
<h3><b>Questions</b></h3>
<div>
<ol>
<li>Describe the shape of these cells.</li>
<li>Are they living or dead cells?</li>
<li>Suggest their function.</li>
</ol>
</div>
</div>
</div>
</div>

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Sclerenchyma Tissue

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Sclerenchyma Tissue

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