Histology Notes - Medicinal Plants (PDF)

## 3.5 سكشن 1 نباتات طبية ### الفرقة الأولي صيدلة ### جنيرال + كلينيكال ### مكتبة ابو صلاح ## What is a microscope? - A microscope is an instrument used to see objects that are too small to be seen by the naked eye. - "Microscope" comes from the words "micro" and "scope," where "micro" means s...

## 3.5 سكشن 1 نباتات طبية ### الفرقة الأولي صيدلة ### جنيرال + كلينيكال ### مكتبة ابو صلاح ## What is a microscope? - A microscope is an instrument used to see objects that are too small to be seen by the naked eye. - "Microscope" comes from the words "micro" and "scope," where "micro" means small or tiny, and "scope" means to view or observe. - Microscopes are therefore instruments to see tiny things. ## A compound microscope is the most common type of light (optical) microscopes. - "Compound" refers to the microscope having more than one lens. - Compound microscopes generate magnified images through an aligned pair of an objective lens and the ocular lens. - In contrast, simple microscopes have only one convex lens and function more like glass magnifiers. ## Parts of a compound microscope - **Eyepiece (Ocular lens)** - Interpupillary adjustment - Eyepiece tube - Head - **Diopter adjustment** - **Nosepiece** - **Objective lens** - Stage clips or slide holder - Aperture - Condenser - Iris Diaphragm - **Illuminator** - **Arm** - **Specimen Stage** - Fine focus - Coarse focus - Stage controls - **Base** - Brightness adjustment - Light switch **Major structural parts of a Compound microscope** - Head - Arm - Base - Binocular - Monocular **Note:** When carrying a compound microscope, always hold it by holding both the arm and base simultaneously, like the image below. - Grab the metal support arm - Hold the bottom of the base ## Eyepiece tube - The eyepiece tube carries the eyepiece lens. - The eyepiece tube holds the eyepiece at the right place that aligns perfectly with the objective lenses. - The eyepiece tube also places the eyepiece and the objective lenses within a distance range to generate in-focus images. - **Monocular** - **Binocular** - **Trinocular** ## Objective lenses are the primary optical lenses for specimen visualization on a microscope. - Objective lenses collect the light passing through the specimen and focus the light beam to form a magnified image. - Objective lenses are the most important parts of a microscope. - A compound microscope comes with 3 or 4 objective lenses. The most common setting is: - **1Scanning objective lens (4x)** - A scanning objective lens provides the lowest magnification power of all objective lenses. - The name "scanning” objective lens comes from the fact that they provide observers with enough magnification for a wide overview of the slide, essentially a "scan” of the slide. - **2Low power objective lens (10x)** - The low power objective lens has more magnification power than the scanning objective lens, and it is one of the most helpful lenses for general viewing purposes. - **3High power objective lens (40x)** - the high-powered objective lens (also known as the "high dry" lens) is ideal for observing fine details within a specimen sample. - **40il immersion objective lens (100x)** - The oil immersion objective lens provides the most powerful magnification. However, the refractive index of air and your glass slide are slightly different, so a special immersion oil must be added to bridge the gap. Without immersion oil, the 100x lens will not function correctly. The specimen appears blurry, and you will not achieve an ideal magnification or resolution. **Note Please!** - Start your observations using the microscope on the lowest magnification setting To avoid breaking the microscope slide with the objective lens. - Do not let your lens kiss the slide ## How to calculate the magnification power? - To obtain the total magnification power, multiply the magnification of the eyepiece and objective lens used. - **For example:** 10]x eyepiece] x [40x objective] = 400x total magnification - 50x-to-1000x-field-of-view - magnification 50x 100x 200x 400x 630x 1000x - Vicia root tip ## When turning the nosepiece, grasp - grasp the nosepiece correctly ## Specimen stage - The stage is a flat platform that supports the slides. - The stage has an opening (called aperture) for the illuminating beam of light to pass through. - The stage clips hold the slides in place. - The microscope has a mechanical stage, the slide secured on the slide holder can be moved in two perpendiculars (X-Y) directions by turning two knobs. - One knob moves the slide left and right, and the other moves it forward and backward. - The mechanical stage provides more stable movements of the specimen slide instead of having to move it manually. ## Coarse and fine focus knobs - Two adjustment knobs are used to focus the microscope: fine focus knob and coarse focus knob. - Both knobs can move the stage up and down. - Use the coarse focus knob to bring the specimen into approximate or near focus. - Then, use the fine focus knob to sharpen the focus quality of the image. - When viewing with a high power objective lens, carefully focus by only using the fine knob. ## Illuminator - The illuminator is the light source for a microscope, typically located in the base of the microscope. - Halogen bulbs are commonly used to provide a steady light source. - Currently, LED lights are becoming more and more popular. ## Condenser - Condensers are lenses that are used to collect and focus light from the illuminator into the specimen. - Condensers can be found under the stage often in conjunction with an iris diaphragm. - **Aperture** - Lower the condenser/diaphragm part to the bottom - Raise the part to a working position - **Abbe Condenser with Iris Diaphragm** - Switch to open or close field diaphragm - **Illuminator** - **Condenser centering screws** ## Compound microscopes have more than one lens to generate high magnification images of flat, thin specimens. - There are three major structural parts of a microscope: Head, Base, and Arm. - Always lift a microscope by holding both the arm and base with two hands. - There are two major optical lens parts of a microscope: Eyepiece (10x) and Objective lenses (4x, 10x, 40x, 100x). - Total magnification power is calculated by multiplying the magnification of the eyepiece and objective lens. - The illuminator provides a source of light. - The light is focused by the condenser and passing through the specimen placed on the stage. - The light is then collected and formed an image by an objective lens. - We see the magnified images through the eyepiece. - A clear image needs perfect focusing by adjusting the coarse and fine focus knobs. - Iris Diaphragm and Abbe condenser are essential for clear images of high magnification. ## Plant cell Anatomy - Every living organism falls into one of two groups: eukaryotes or prokaryotes. - Cellular structure determines which group an organism belongs to. - **Prokaryotes** are unicellular organisms that lack membrane-bound structures, the most noteworthy of which is the nucleus. - Prokaryotic cells tend to be small, simple cells, measuring around 0.1-5 µm in diameter EX bacterial cell. - **Eukaryotes** are organisms whose cells have a nucleus and other organelles enclosed by a plasma membrane. - Organelles are internal structures responsible for a variety of functions, such as energy production and protein synthesis EX plant cell & Animal cell. ### Prokaryotes - No nucleus - Small and simple - No organelles - Very abundant - Unicellular - All are bacteria ### Both - Have ribosomes - Have DNA - Have cytoplasm - Some have cell membrane - Some have flagella ### Eukaryotes - Have nucleus - Have organelles - Have a cytoskeleton - Have a cell membrane - Can be multicellular or unicellular - Some have a cilia ## Plant Cell - Cell Wall - Ribosomes - Endoplasmic Reticulum - Plasma Membrane - Golgi Apparatus - Mitochondria - Chloroplasts - Central Vacuole ## Animal Cell - Small or No Vacuole - Centrioles and Centrosomes - Flagella ## All the higher plants are built-up of small living units called cells. - Although they are at first more or less of the same size, they grow and change into size and shape approximate to the functions they take in the life of the plant as a whole. - Each cell consists of living and non-living materials. - A living plant cell has three distinct regions: - the cell wall; - the protoplasm; and - the vacuoles. - The protoplasm is living but the cell wall and vacuoles are non-living. ## Onion cell under microscope - A Typical plant cell - Polyhedral cells with rounded angles. - Wide lumen. - Without intercellular spaces ## Preparing Unstained Red Onion Cells for a Microscope Slide 1. Cut off a small piece of red onion. 2. Use forceps or your fingernail to peel away a very thin layer of skin from the inside. 3. Spread and smooth the onion skin flat on the middle of the microscope slide. 4. Add 2 - 3 drops of distilled water. 5. Carefully place a cover slip over the skin. 6. Gently dab the edges with a paper towel to absorb any excess solution. 7. Place the microscope slide onto the stage and secure with the stage clips. 8. Ensure the magnification is at the lowest setting to begin with (usually 4x or 10x). 9. Use the adjustment knobs to focus on and observe the cell at a higher magnification. - **Forceps** - **red onion** - mount with distilled water - mount with salt solution - View in the microscope