Identification of Parenchyma, Collenchyma and Sclerenchyma tissues in plants,
striped, smooth and cardiac muscle fibres and nerve cells in animals from prepared
slides. Drawing of their labelled diagrams write it's AIM, procedure material required, conclusion ,precautions
Answers
Paremchyma and Collenchyma are living tissues where as Sclerenchyma is dead tissue making it three different plant tissues.
The striped, smooth and cardiac muscles , fiber and nerve cells are part of a tissue system and we can use histological staining to prepare its slides.
Explanation:
1. Parenchyma
i. Consists of a thin wall of living cells.
ii. This thin wall is usually made up of cellulose.
iii. Involved in food storage.
2. Collenchyma
i. Consists of uneven thin cell wall of living cells.
ii. The cell walls are made up of pectin and hemicellulose.
iii. They are the chief mechanical tissue in young plants especially dicot stems.
3. Sclerenchyma
i. Consist of dead cells and have a hard thick cell walls.
ii. These cell walls are made up of lignin.
iii. It's mainly a mechanical tissue.
The Five Steps of Histology Slide Preparation are as follows.
1. Tissue fixation
Most specimens are fixed in 10% neutral buffered formalin. The optimum formalin-to-specimen volume ratio should be at least 10:1 (e.g., 10ml of formalin per 1 cm3 of tissue). This will allow most tissues to become adequately fixed within 24-48 hours. Formalin containers should be capped and leak-proof and labelled correctly.
2. Specimen Transfer to Cassettes
After fixation, specimens are trimmed using a scalpel to enable them to fit into an appropriately labelled tissue cassette. They should be not more than 4 mm thick. The filled tissue cassettes are then stored in formalin until processing begins.
3. Tissue Processing
The tissue processing is done using paraffin block.
i. Dehydration, which involves immersing your specimen in increasing concentrations of alcohol to remove the water and formalin from the tissue.
ii. Clearing, in which an organic solvent such as xylene is used to remove the alcohol and allow infiltration with paraffin wax.
iii. Embedding, where specimens are infiltrated with the embedding agent – usually paraffin wax. The tissue becomes surrounded by a large block of molten paraffin wax, creating what is now referred to as the “block”. Once the block solidifies, it provides a support matrix that allows very thin sectioning.
4. Sectioning
i. Wax is removed from the surface of the block to expose the tissue.
ii. are chilled on a refrigerated plate or ice tray for 10 minutes before sectioning.
iii. A microtome is used to slice extremely thin tissue sections off the block in the form of a ribbon.
Most tissues are cut at around 5 µm. the tissue ribbons are carefully transferred to a warm water bath. Here they are allowed to float on the surface, and can then be scooped up onto a slide placed under the water level. Charged slides work best for this process – they improve tissue adhesion to the glass, and help to reduce the chance of sections washing off the slide during staining.
Slides should be clearly labelled, and then allowed to dry upright at 37 dgree Celsius for a few hours to gently melt the excess paraffin wax, leaving the tissue section intact.
5. Staining
Most cells are transparent and appear almost colorless when unstained. Histochemical stains (typically hematoxylin and eosin) are therefore used to provide contrast to tissue sections, making tissue structures more visible and easier to evaluate. Following staining, a coverslip is mounted over the tissue specimen on the slide, using optical grade glue, to help protect the specimen.
Answer: As we know plant and animal tissues are different in respective properties and their function.
Explanation:
AIM:- identification of parenchyma, collenchyma, and sclerenchyma tissues in plants.
Material required:- prepared slide of parenchyma, collenchyma, sclerenchyma, compound microscope.
Theory:- Group of cells is known as tissue, cells which are similar in structure and work together to achieve a particular function.
The main type of plant tissue are:-
I. Parenchyma
These tissue cells are isodiametric.
Cells have inter-cellular spaces in between them.
Parenchymatous cells possess a large central vacuole and peripheral cytoplasm with the nucleus.
These are commonly present in the soft parts of plants like roots, flowers, leaves, etc.
The function of parenchymatous cells is storage, photosynthesis, etc.
The important functions of parenchymatous cells are storage, photosynthesis, etc.
2.CoIIenchyma
- collenchymatous cells are somewhat oval to elongated.
- Every cell contains large vacuoles and peripheral cytoplasm with a prominent nucleus.
- The corner of cells is thick and thickening comprising cellulose and pectin.
- Thickenings are present at the corners of cells. Thickening comprises cellulose and pectin.
- Intercellular space is not present in these cells.
- These cells are generally present below the epidermis in petioles, leaves, and stems.
- Mainly it provides mechanical strength.
3. Sclerenchyma
- Sclerenchyma tissue cells are dead and these possess highly thick walls. Thickenings comprise lignin.
- These are two types of cells:- 1) fibers which have elongated cells with tapering ends and 2) sclereids, these are roughly isodiametric cells and have narrow cavities. these are called stone cells.
- Pits are present in these cells which act as connections with adjacent cells.
- Sclerenchyma's main function is to give support and mechanical strength to the plant.
Procedure:-
- Prepared slides of all plant tissues were observed one by one.
- The microscope was set on lower power to focus on the slide and then set on high power to observe the structure and tissue type.
- Study the characters and draw the diagrams in the register.
Precautions:-
- The microscope should be handled carefully.
- The slide should always focus on lower power(10x) than high lower(40x).
AIM 2:- To identify striped, smooth, and cardiac muscle fibers and nerve cells in animals from prepared slides.
MATERIALS REQUIRED
Prepared slides of striped, smooth, cardiac, and nerve cells, compound microscope.
Theory:- tissue is a group of cells that have a similar structure, origin, and functions.
1. Striped or Skeletal Muscles
- These are also known as striated and these are cylindrical, elongated, and enclosed in a membrane called sarcolemma.
- These muscle cells are multi-nucleated and the presence of light and dark bands gives a striped appearance to it.
- These are attached to the skeleton of the body and these are also voluntary muscles.
2. Smooth Muscles
- These are also known as Non- striated muscles.
- These cells have spindle shapes and the nucleus is present in the center.
- These muscles don't have striations( i.e., no light and dark bands).
- These are involuntary muscles and are commonly found in alimentary canals and blood vessels.
3. Cardiac Muscles
- These muscle cells are long, branched, and uninucleated.
- Intercalated discs are present and these also show the alternate light and dark bands.
- Muscles are involuntary and also responsible for rhythmic contraction and relaxation of the heart.
- Cardiac muscles are mainly present in the heart walls.
4. NERVE CELL
- These cells are made up of a cell body or cyton with only one nucleus and cytoplasm.
- Dendrons are parts that consist of small cytoplasmic projections that arise from cyton. Dendrons are further divided into dendrites.
- Long cytoplasmic projection generated from the cell body is known as an axon
- Axon may have myelin sheath over them. these are known as a myelinated nerve fibers.
- These cells help in the conduction of nerve impulses.
Precautions
- The microscope should be handled properly.
- The slide should focus on lower power and then focus on high power.
