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Identifying Stages of Mitosis

Pearson
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[MUSIC PLAYING] Identifying the stages of mitosis using a compound light microscope. Understanding how to properly identify the stages of mitosis is fundamental to any anatomy and physiology laboratory course. In this video, we will recall the major events of each phase of mitosis as well as identify the stages of mitosis using a compound light microscope. Recall that the cell cycle is a series of events leading up to cellular division. We will review those events in this video, but you may wish to review the A&P Flix video "The Cell Cycle" for more in-depth explanation. The cell cycle is made up of interphase and the M phase. During interphase, cellular growth and DNA replication occur. During the M phase, cellular division is accomplished and cytokinesis or cytoplasm division. Mitosis is made up of four stages; prophase, metaphase, anaphase, and telophase. Let's take a look at how to locate and identify the stages of mitosis using a compound light microscope. Most mitosis slides will have several sections of a blastula, which is a ball of rapidly dividing embryonic cells, each in various stages of the cell cycle. Before you begin, you may like to review the pre-lab video "Viewing Objects Through the Compound Light Microscope." To start, make sure the scanning, or 4x objective lens, is in use. Place the slide on the stage and locate one of the blastulas. Use the coarse adjustment knob to bring the image into approximate focus, then use the fine adjustment knob and focus until the image becomes clear. You will not be able to distinguish the stages of mitosis at this magnification. Next, increase the magnification to low power, or 10x magnification, and use the fine adjustment knob to focus the image. At this magnification, you will be able to see chromosomes. Recall that chromatin condenses during prophase. The visible chromosomes will appear as dark areas within the cell. Adjust the light as needed. We will now increase the magnification to high power, or 40x, and focus the image. It is at this magnification that you will be able to distinguish between the various stages of mitosis. Fine focus, then slowly move the slide using the mechanical stage adjustment knobs to locate and identify each stage of mitosis. Most of the cells seen will be an interphase. During interphase, the nuclear envelope is still intact, and the chromatin has not yet condensed. Using the stage adjustment knob, slowly move the slide until you locate a cell in which the chromosomes can be clearly seen. It is important to note that you may not see all four of the stages of mitosis in a single blastula. Now let's take a look at each of the four stages of mitosis. Here we see prophase. The chromosomes are stained dark and clustered in the center. The remnants of the nuclear envelope may still be visible. This one is in metaphase. All of the chromosomes are aligned at the metaphase plate, or equator, and appear to be in a line across the center of the cell. Asters also may be seen here. This cell is in anaphase. You can see the sister chromatids begin to separate as they are pulled apart by the spindle fibers. This cell is in telophase phase, and we can see the cleavage furrow has begun to form. With time, you'll become more efficient at locating and identifying the stages of mitosis. As with anything, practice makes perfect.
[MUSIC PLAYING] Identifying the stages of mitosis using a compound light microscope. Understanding how to properly identify the stages of mitosis is fundamental to any anatomy and physiology laboratory course. In this video, we will recall the major events of each phase of mitosis as well as identify the stages of mitosis using a compound light microscope. Recall that the cell cycle is a series of events leading up to cellular division. We will review those events in this video, but you may wish to review the A&P Flix video "The Cell Cycle" for more in-depth explanation. The cell cycle is made up of interphase and the M phase. During interphase, cellular growth and DNA replication occur. During the M phase, cellular division is accomplished and cytokinesis or cytoplasm division. Mitosis is made up of four stages; prophase, metaphase, anaphase, and telophase. Let's take a look at how to locate and identify the stages of mitosis using a compound light microscope. Most mitosis slides will have several sections of a blastula, which is a ball of rapidly dividing embryonic cells, each in various stages of the cell cycle. Before you begin, you may like to review the pre-lab video "Viewing Objects Through the Compound Light Microscope." To start, make sure the scanning, or 4x objective lens, is in use. Place the slide on the stage and locate one of the blastulas. Use the coarse adjustment knob to bring the image into approximate focus, then use the fine adjustment knob and focus until the image becomes clear. You will not be able to distinguish the stages of mitosis at this magnification. Next, increase the magnification to low power, or 10x magnification, and use the fine adjustment knob to focus the image. At this magnification, you will be able to see chromosomes. Recall that chromatin condenses during prophase. The visible chromosomes will appear as dark areas within the cell. Adjust the light as needed. We will now increase the magnification to high power, or 40x, and focus the image. It is at this magnification that you will be able to distinguish between the various stages of mitosis. Fine focus, then slowly move the slide using the mechanical stage adjustment knobs to locate and identify each stage of mitosis. Most of the cells seen will be an interphase. During interphase, the nuclear envelope is still intact, and the chromatin has not yet condensed. Using the stage adjustment knob, slowly move the slide until you locate a cell in which the chromosomes can be clearly seen. It is important to note that you may not see all four of the stages of mitosis in a single blastula. Now let's take a look at each of the four stages of mitosis. Here we see prophase. The chromosomes are stained dark and clustered in the center. The remnants of the nuclear envelope may still be visible. This one is in metaphase. All of the chromosomes are aligned at the metaphase plate, or equator, and appear to be in a line across the center of the cell. Asters also may be seen here. This cell is in anaphase. You can see the sister chromatids begin to separate as they are pulled apart by the spindle fibers. This cell is in telophase phase, and we can see the cleavage furrow has begun to form. With time, you'll become more efficient at locating and identifying the stages of mitosis. As with anything, practice makes perfect.