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MITOSIS AND MEIOSIS
Lab Format: This lab is a remote lab activity.
Relationship to Theory: In this lab you will be examining the underlying processes that make up
the cell cycle.
Instructions for Instructors: This protocol is written under an open source CC BY license. You
may use the procedure as is or modify as necessary for your class. Be sure to let your students
know if they should complete optional exercises in this lab procedure as lab technicians will not
know if you want your students to complete optional exercise.
Remote Resources: Primary - Microscope, Secondary - Mitosis and Meiosis slide set.
Instructions for Students: Read the complete laboratory procedure before coming to lab. Under
the experimental sections, complete all pre-lab materials before logging on to the remote lab,
complete data collection sections during your on-line period, and answer questions in analysis
sections after your on-line period. Your instructor will let you know if you are required to complete
any optional exercises in this lab.
Contents
MITOSIS AND MEIOSIS .................................................................................................. 1
Learning Objectives ..................................................................................................... 2
Background Information ............................................................................................... 2
Equipment ................................................................................................................... 6
Preparing to Use the Remote Web-based Science Lab (RWSL) ................................. 7
Introduction to the Remote Equipment and Control Panel ........................................... 7
Experimental Procedure: ............................................................................................. 8
Exercise 1: Mitosis in Animal and Plant Cells .............................................................. 8
Exercise 2: Calculate the Percentage of Time Spent in Each Stage of Mitosis ........... 9
Exercise 3: Growth in the Onion Root........................................................................ 11
Exercise 4: Stages of Meiosis .................................................................................... 12
Exercise 5: Meiosis in Humans (Optional) ................................................................. 13
Summary Questions: Mitosis and Meiosis Experiment .............................................. 14
Appendix A - Introduction to the RWSL Microscope .................................................. 16
Appendix B – Loading Slides ..................................................................................... 17
Appendix C - Microscope Control .............................................................................. 18
Appendix D – Manipulating the Microscope Image .................................................... 19
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Appendix E – Capturing and Saving a Microscope Image ......................................... 21
Appendix F - Camera Controls .................................................................................. 23
LEARNING OBJECTIVES
After completing this laboratory experiment, you should be able to do the following things:
1.
2.
3.
4.
5.
6.
Describe the cell cycle.
Identify the stages of mitosis from prepared slides.
Calculate the percentage of time a cell spends in each stage of the cell cycle.
Quantify the relationship between cell division and cell growth.
Recognize the processes of meiosis and how it differs from mitosis.
Identify support cells from human spermatogenesis and oogenesis. (Optional)
BACKGROUND INFORMATION
If I asked you “Where do cells come from?” what would you answer? In modern biology our
understanding of a the cell as the basic building block of life is codified in a set of principles called the
Cell Theory which was first codified by Schleiden and Schwann in 1838-39. The cell theory is second
only to the theory of evolution by natural selection in understanding the relatedness of life. Cell
Theory says the following:
1. All living organisms are composed of one or more cells.
2. Cells are the basic building blocks of all life.
3. All cells are descended from a preexisting cell.
While these may seem like relative simple points it took scientists several centuries to produce the
cell theory.
The development of the cell theory directly follows the development of the microscope. The name
“cell” was coined by Robert Hooke6 in 1665. While observing a piece of cork under his microscope he
thought that the microscopic units that made up the cork looked like the rooms, or “cella” in Latin,
that monks lived in. This was closely followed by the discovery of single celled organisms by Antoni
van Leeuwenhoek3-5 in 1676. Leeuwenhoek discovered motile microscopic particles by examining
scrapings from his teeth under his microscope. In 1838 Metthias Schleiden7 and Theodor Schwann8
presented evidence that all plants and animals are composed of cells. However, there were still some
questions as to where cells came from, as Schleiden believed cells formed through a process of
crystallization. This theory was simply a variant on the belief of Aristotle that life could come into
existence by spontaneous generation.
It was not until the 1850s that a group of scientist was able to show that new cells were produced
from preexisting cells9. However, most scientists believe the definitive test disproving spontaneous
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creation of microbial life was conducted by Louis Pasteur in 186210. In Pasteur’s experiment two
flasks were each set-up with bacterial growing broth (a liquid that is conducive to the growth of
bacteria) and sterilized. Both flasks were left open to the air but in such a way that dust could enter
only flask 1 not flask 2. After a period of time bacteria growth was seen in only flask 1 and not in flask
2. This showed that dust (bacteria) had to be added to the broth in order for bacteria to grow.
In this lab we will be examining the mechanism underlying the third principle of the cell theory “that
all cells are descended from preexisting cells”. There are two processes involving the production on
new cells, the first process, mitosis, is used for growth and to replace old or dead cells. The second
process, meiosis, is used to produce gametes (egg and sperm) cells that are used for sexual
reproduction. An important point to keep in mind is that we name the type of cell cycle based on what
is happening to the nucleus and genetic material.
The mitotic cell cycle (see figure 1) is used to produce new somatic (body) cells in the organism. The
mitotic cell cycle in the simplest form is composed of two parts Interstage and Mitosis. However,
each of these parts can be further divided. Mitosis can be divided into four parts: Prostage, Metastage,
Anastage, and Telostage which will be described
below. Mitosis, in fact, means the division of the
nucleus to produce two identical daughter cells.
The division of the cell itself is called cytokinesis
and overlaps telostage but is not actually
classified as part of it. Interstage (the part of
the cell cycle between actual divisions) is
composed of three parts Gap1 (sometimes
referred to as growth1) the cell grows and
performs normal cellular functions, Synthesis (s
stage) DNA is replicated, and Gap2 (sometimes
referred to as growth2) is where the cellular
organelles are replicated. There is one
additional stage to the cell cycle Gap0. A cell that
has stopped cycling (dividing) either
temporarily or permanently has entered Gap0.
The different stages of the cell cycle were identified as morphological changes by Waclaw Mayzel in
18751,2. All these morphological changes can be observed in a compound microscope. During
Interstage (figure 2A) there is a clearly defined nuclear envelope filled with dispersed chromosomes.
As the cell enters Prostage (figure 2B) the chromosomes condense and the mitotic spindle forms. At
this point each chromosome is composed of two sister chromatids joined at the centromere.
Additionally, the nuclear envelope breaks down and the mitotic spindle begins attaching to the
chromosomes at the centromere. (In some texts the breakdown of the nuclear envelope and the
attachment of the mitotic spindle to the chromosomes is listed as an additional stage Prometaphase).
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In Metaphase (figure 2C) the chromosomes line up in the middle of the cell forming a structure called
the metaphase plate. During Anaphase (figure 2D) the centromere splits and each chromatid now a
chromosome is pulled to opposite sides of the cell. In the last stage Telophase (figure 2E) the
chromosomes become less condensed, two new nuclei form and the mitotic spindle de polymerizes.
This officially ends mitosis which as mentioned before is the replication and division of the nucleus.
The cell cycle ends with cytokinesis, the division of the cytoplasm, which often overlaps late
telophase.
The other type of cell cycle is called meiosis and is used in sexual reproduction to produce gametes
(sperm and egg in most animals and plants). In plants and animals each organism contains two copies
of each chromosome; this is called diploid. In order for sexual reproduction to occur properly the
number of chromosomes need to be reduced by half; which is called haploid. If the chromosome
number was not reduced by half then each new generation would have twice the number of
chromosomes as the previous organism; which is called polyploidy. In many organisms a state of
polyploidy causes biological defects.
Mechanistically meiosis differs from mitosis in that two rounds of cell division occur, referred to as
meiosis I and meiosis II, with only one round of DNA synthesis. Figure #3 shows the stages of meiosis
were there are differences between the corresponding mitotic and meiotic stages. This produces 4
haploid cells; the number of mature gametes varies depending on whether the final mature cell is a
sperm cell or egg cell (Figure 3). In meiosis I S stage occurs as normal. The first difference between
mitosis and meiosis I occurs in Prophase I, during Prophase I the homologous chromosomes pair up
and exchange genetic material by crossover (Figure 3). This exchange of genetic material increases
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the genetic variation in the offspring. The
next difference occurs in anaphase I,
during anaphase I instead of the
centromere dividing it stays connected
and the homologous chromosomes are
segregated to the opposite poles (Figure
3). During Cytokinesis I we see the first
difference between spermatogenesis
(sperm formation) and oogenesis (egg
formation). During cytokinesis of the egg
the cytoplasm divides unequally with one
of the daughter cells getting most of the
cytoplasm, the smaller cell is called a polar
body (Figure 3B). The presperm cells
undergo an equal cytokinesis (Figure 3A).
The cells will then enter a second cell cycle, meiosis II, without replicating DNA. The length of
interphase between meiosis I and meiosis II varies from nonexistent too years depending on the
organism. In meiosis II during Anaphase II the kinetochore divides and the sister chromatids are
pulled to opposite poles of the cell. Again the in oogenesis the cell undergoes unequal cytokinesis
producing an oogonia and another polar body, while the sperm cells divide equally. This produces
four haploid spermatocytes in the male line and one haploid oogonia and 2 or 3 haploid polar bodies
in the female line. The spermatocytes and oogonia go on to mature in to sperm and egg cells, which
will give rise to a new generation.
Now that we have and understanding of the mechanisms of mitosis and meiosis it is clear how each
separately links to the third principle of the cell theory: all cells descend from preexisting cells. For
instance we know that new somatic cells arise from mitosis, when an older cell divides. Additionally,
we know that the development of a new multi cellular organism starts with the fusion of two gametes
(fertilization) which produces a zygote. The remaining question though is how does mitosis and
meiosis relate to each other. The answer to this question depends on whether we are talking about
a multi cellular animal or plant. In multicellar animals the zygote divides a few times mitotically then
the cells are separated into two populations one population will continue to divide mitotically and
will go on to form all the somatic cells. The second population will form the germline (Figure 4A). In
plants the first few stages are the same, the difference occurs in that a population of cells is not set
aside to form a germline (Figure 4B). Instead germline cells are recruited from the somatic cells
when they are needed.
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References:
Medycyna, czasopismo tygodniowe dla lekarzy (1875; 3(45), 409/0412)
Centralblatt f. die Med. Wissenschaften (1875; 50: 849–852)
Dobell, C. Antony van Leeuwenhoek and His “Little Animals” (Dover, New York, 1960).
Wolpert, L. Curr. Biol. 6, 225–228 (1995).
Singer, S. A Short History of Biology (Clarendon, Oxford, 1931).
Westfall, R. S. Hooke, Robert in Dictionary of Scientific Biography Vol. 7 (ed. Gillespie, C.) 481–
488 (Scribner, New York, 1980).
Schleiden, M. J. Arch. Anat. Physiol. Wiss. Med. 13, 137–176 (1838).
Schwann, T. Mikroskopische Untersuchungen über die Übereinstimmung in der Struktur und
dem Wachstum der Tiere und Pflanzen (Sander’schen Buchhandlung, Berlin, 1839).
Mayr, E. The Growth of the Biological Thought (Belknap, Cambridge, MA, 1982).
Pasteur, L. A. Ann. Sci. Nat. (part. zool.) 16, 5–98 (1861).
EQUIPMENT




Paper
Pencil/pen
Slides
o Onion Root Tip
o Whitefish Blastula
o Mammal Graafian Follicles
o Human Testis
o Ascaris lumbricoides
o Grasshopper Testis
Computer with Internet access (for the remote laboratory and for data analysis)
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PREPARING TO USE THE REMOTE WEB-BASED SCIENCE LAB (RWSL)
Click on this link to access the Installguide for the RWSL: http://denverlabinfo.nanslo.org
Follow all the directions on this webpage to get your computer ready for connecting to the
remote lab.
INTRODUCTION TO THE REMOTE EQUIPMENT AND CONTROL PANEL
Watch this short tutorial video to see how to use the RWSL control panel:
http://denverlabinfo.nanslo.org/video/microscope.html
There are appendices at the end of this document that you can refer to during your lab if
you need to remind yourself how to accomplish some of the tasks using the RWSL
control panel.
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EXPERIMENTAL PROCEDURE:
Once you have logged on to the microscope you will perform the following Laboratory procedures:
EXERCISE 1: MITOSIS IN ANIMAL AND PLANT CELLS
Pre-lab:
New cells are produced in animals and plants by the
division of old cells. These new cells can be used for growth
or to replace dead or damaged cells. As stated in the
introduction, the cell cycle is divided into two parts the
replication and division of the genetic material (mitosis)
and the division of the cytoplasm (cytokinesis). In this
experiment you will use prepared slides of an onion root tip
and a whitefish blastula to identify the stages of mitosis.
The onion root tip is divided into four sections based on the
behavior and function of the cells (Figure 5). The first
region is the root cap which protects the growing root. The
second is the meristeam, a region of highly mitotically active
cells. Then there are the elongation regions where cells are
growing, and then lastly the maturation region where cells
become fully mature root cells. While the onion root tip is
divided into four cell population (root cap, meristeam,
elongation and maturation) at the developmental stage of development you are looking at, the cells
in the white fish blastula are a uniform population.
Pre-lab Questions:
1. Do you think you will see any differences between plant or animal cells? What differences do
you think you will see?
2. Rewrite your answer to question one in the form of an If … Than … hypotheses.
Data Collection:
3. Select the prepared slide of the whitefish blastula using the RWSL microscope controls.
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4. Locate the blastula then increase the magnification and working as a group identify a cell in
each stage of mitosis. Use the “capture image” feature on the RWSL microscope control panel
to capture an image of each stage. (Each member of your group should use the microscope to
identify at least one stage.)
5. Select the prepared slide of the onion root tip using the RWSL microscope controls.
6. Locate the onion root tip then increase the magnification and working as a group identify the
stages of mitosis. Use the “capture image” feature on the RWSL control panel to capture an
image of each stage. (Each member of your group should use the microscope to identify at
least one stage.)
Analysis:
7. Use the insert and textbox feature on your computer word processing program to label the
plasma membrane, chromosomes, mitotic spindle, nuclear membrane, and centriole, for each
image as appropriate. [Place your images below.]
8. Use the insert and textbox feature on your computer word processing program to label the
plasma membrane, chromosomes, mitotic spindle, nuclear membrane, and centriole, for each
image as appropriate. [Place your images below.]
9. Think back to the pre-lab questions about differences in plant and animal cell mitosis. Were
you prediction correct? What, if any, differences did you actual see?
10. If your predictions were incorrect revise your hypotheses based on your new understanding
of the differences between mitosis in plants and animals.
EXERCISE 2: CALCULATE THE PERCENTAGE OF TIME SPENT IN EACH STAGE OF MITOSIS
Pre-lab
At the time when the whitefish blastula slide was prepared, the cells were arrested at their current
stage within the cell cycle by fixation, which is a chemical reaction that stops the biological process
in the cell. Fixation also preserves the tissues by immobilizes the cells, organelles, and proteins
through chemical cross linking. The duration of each stage of the cell cycle in the blastula can be
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estimated by determining the proportion of cells arrested at each stage of mitosis with respect to the
number of cells in interstage.
Let’s assume that you examined a slide and determined the stage at which 100 cells were arrested by
fixation. It is known that whitefish blastula cells take about 24 hours to complete the cell cycle. By
determining the percentage of cells in each stage of mitosis and in Interstage, you can calculate the
amount of time spent in each stage. For example, if ten cells out of 100 were found to be in Prostage,
the percentage of cells is 10/100 x 100 = 10%. This shows that any one of the hypothetical cells
spends 10% of the time in Prostage, so they spend 0.10 x 24 hours or 2.4 hr (2 hr and 24 min) in that
stage.
Pre-lab Questions:
1. Create a table to record your data in. [Insert it below]
Data Collections:
2. Select the whitefish blastula slide; select an area of a blastula so that your entire field of view
is filled with cells.
3. Count and record the number of cells in each stage of the cell cycle in your field of view. Enter
this information in the table you created in the pre-lab. (Each group member should count at
least one field of view.)
4. Repeat the step 3 three times with a new field of view each time.
Analysis:
5. Calculate the percentage of time the cells spent in each stage of the cell cycle for each field of
view independently. Create a new table to hold this information.
6. Now sum the numbers from all four data sets and use the totals to calculate the percentage
of time the cells spent in each stage of the cell cycle. Place this data in the same table as the
data from question 5. [Insert Table Below]
7. Compare the time the cells spent in each stage of the cell cycle from the summed data to that
from the individual data do you notice any differences?
An important part of validating data is determining how repeatable the data are. A simple way to
examine repeatability is to look at the variability of the data. One way to calculate this variability is
by using a standard deviation calculation. The equation to calculate standard deviation is =
1
√ ∑N
(x − μ)2 . This equation is actually quite simple in this case: n is the number of samples
n i=1 i
(number of fields of views you counted), xi is one of the numbers in your data set (one field of view),
μ is the average of the numbers in the data set (average of all field of views), and Σ means you sum
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the numbers. As an example, suppose we had four numbers 1.0, 2.0, 3.0, & 4.0 the average of these
(1−2.5)2 +(2−2.5)2 +(3−2.5)2 +(4−2.5)2
numbers is 2.5 therefore the standard deviation of this set is√
4
= 1.1.
8. In the above example of a standard deviation calculation your calculator would have
displayed the result as 1.11803398… Why did we only display 1.1 as the answer?
9. Calculate the standard deviation for each of your cell stages. List the length of time each cell
spends in each stage of the cell cycle with its standard deviation below, in this format: time
in stage +/- standard deviation.
EXERCISE 3: GROWTH IN THE ONION ROOT
Pre-lab:
In this exercise we are going to study the growth of the onion root. Growth can be effected by both
the number of cells and the size of the cells. You will look at four areas of the onion root the tip, one
each in: the cap cells, the meristeam, the elongation region, and the maturations region. In each region
you will determine the length of the cells and the percentage of cells that are in any stage mitosis
(often called the mitotic index).
Pre-lab Questions
1. Based on your knowledge of the cell cycle, what kind of relationship do you think you will see
between cell size and the mitotic index?
2. Using the If … Than … format rewrite your answer to question on in the form of a hypothesis.
3. Create a table to record your data. [insert the data table below]
Data Collection:
4. Select the onion root tip slide using the RWSL microscope control. (Each member of the group
should collect data from a region)
5. Position the microscope so that you are looking at the cap cells.
6. Count all the cells in the field of view; count how many of them are in mitosis.
7. Determine how long each cell is.
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8. Position your sample so that you are looking at the meristeam and repeat steps 4&5
9. Position your sample so that you are looking at the elongation region and repeat steps 4&5
10. Position your sample so that you are looking at the maturation region and repeat steps 4&5
Analysis:
11. Calculate the mitotic index for each region. Modify your table form question one and enter
the mitotic index your new table.
12. Calculate the size of the cells for each region and record that in your table from question 11
[Insert your data table below]
13. How does your prediction of the relationship of the mitotic index to cell size correlate to the
data you collected?
14. If needed rewrite your hypothesis in light of the new data you collected.
15. Based on your observations what stage of the cell cycle are the onion root cells that were in
the elongation region likely in?
EXERCISE 4: STAGES OF MEIOSIS
Pre-lab:
Observing the different stages of meiosis is often difficult do to the structure of the organs in which
meiosis and fertilization occur. One way scientist gets around this type of problem is through the use
of model organisms. A model organism is an organism in which a particular biological process is
easily observed or manipulated. Two examples of model organisms used in the study of meiosis are
the grasshopper testis and the Ascaris lumbricoides ovary. The reason that these are good model
organisms for the process of meiosis is that meiotic cells travel down the organ in a liner path. Later
stages of meiosis are farther along in the organ than earlier. For example in a grasshopper testis it is
often possible to observe all stages of both meiosis I and meiosis II. The ovary of the Ascaris
lumbricoides (a nematode worm) is similarly arranged. However, in the case of the Ascaris
lumbricoides ovary you can see the polar bodies produced during oogenesis as their life time is long
enough that they are preserved in the fixed tissue. Additionally, fertilization also occurs in the ovary
allowing for the observation of the pronuclei in early fertilization. In this lab we are going to use
these two model organisms to observe the processes of meiosis and fertilization.
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Pre-lab Questions:
1. Why are we not using human ovaries and testis to observe meiosis and pronuclei?
Data Collection:
2. Select the grasshopper testis slide using the RWSL microscope control panel.
3. Use the “capture image” feature on the RWSL control panel to capture an image of the testis.
4. Select the Ascaris lumbricoides Female slide using the RWSL microscope control panel.
5. Use the “capture image” feature on the RWSL control panel to capture an image of a
developing oocyte with a polar body attached.
6. Use the “capture image” feature on the RWSL control panel to capture an image of a fertilized
egg with an egg and sperm pronuclei.
Analysis:
7. Use the insert and textbox feature on your computer word processing program to label two
cells in meiosis I and two cells in meiosis II. [Place your image below]
8. Use the insert and textbox feature on your computer word processing program to label the
oocyte, polar bodies, and egg and sperm pronuclei as appropriate in the two Ascaris
lumbricoides pictures. [Place your image below]
EXERCISE 5: MEIOSIS IN HUMANS (OPTIONAL)
Pre-Lab:
In humans meiosis occurs in special tissues in specialized organs, the ovary in females and the testes
in males. The biological function of these organs is to isolate, protect, support, and deliver the
gametes. Early in the process of development the cells that will become the gametes temporally exit
the cell cycle and are segregated to a region of the embryo that will become the testes or ovaries. This
process of segregation helps protect the DNA of germline cells from damage in two ways. The first is
that these cells will undergo fewer rounds of division and therefore DNA synthesis then the other
cells in the body. This is important because DNA synthesis is one of the most common ways DNA
modification can occur. Second these cells live inside the structure of the testes or ovary and get some
protection from the outside world. In this exercise we will observe the cells needed to support the
development of the sperm and eggs in humans in this exercise. In addition to identifying fully
developed sperm and eggs.
Pre-lab Questions:
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1. Do you think the appearance of the chromosomes will look any different in the meiotic cell
cycle stages then in the mitotic cell cycle stages you observed earlier, explain
Data Collection:
2. Select the prepared slide of the Mammal Graafian Follicles using the RWSL microscope
control.
3. Use the “capture image” feature on the RWSL microscope control panel to capture an image
of the Mammal Graafin Follicles.
4. Select the prepared slide of the Human Testis using the RWSL microscope control
5. Use the “capture image” feature on the RWSL microscope control panel to capture an image
of the Human Testes.
Analysis
6. Use the insert and textbox feature on your computer word processing program to label the
primary follicle, primary oocyte, secondary follicle and secondary oocyte. [include it below]
7. Use the insert and textbox feature on your computer word processing program to label
seminiferous tubules and mature tailed sperm. [include image below]
8. Was your prediction in question one correct, explain.
SUMMARY QUESTIONS: MITOSIS AND MEIOSIS EXPERIMENT
1. Which is more similar to mitosis: meiosis I or meiosis II? Explain your answer.
2. Can a haploid cell undergo meiosis? Can it divide by mitosis?
3. Why do you expect the diploid number of chromosomes always to be an even number and
never an odd number?
4. How does crossing over contribute to genetic variability? Does this have any evolutionary
significance?
5. How does the cell decide which homologue goes to which pole during anaphase I? How does
this contribute to genetic variability?
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APPENDIX A - INTRODUCTION TO THE RWSL MICROSCOPE
The RWSL microscope is a high-quality digital microscope located in the remote lab
facility. You will be controlling it using a control panel that is designed to give you
complete control over every function of the microscope, just as if you were sitting in front
of it.
You must call into a voice conference to communicate with your lab partners and with
the Lab Technicians. This is very important because only one person can be in control
of the equipment at any one time, so you will need to coordinate and collaborate with
your lab partners.
You take control of the equipment by right-clicking anywhere on the screen and
selecting Request Control. You release control by right-clicking too.
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APPENDIX B – LOADING SLIDES
Clicking on the Slide Loader tab at the top
of the screen will display the controls for
the Slide Loader robot. There can be up to
four cassettes available on the Slide
Loader, and each cassette can hold up to
50 slides. There will be a drop-down list
for each cassette that is available. In the
above example, only cassette #1 is
available on the Slide Loader. You can
click on it to select a specific slide to be
loaded, as in the image below:
Once you select the slide you want to load
on the microscope, click the Load button to
the right of the drop-down list. You will see
a message telling you that the slide is
loading. You can also watch this
happening using the picture-in-picture
(PIP) camera (see Appendix F - Camera
Controls).
Notice that when a slide is actually on the
microscope (or when it is being loaded or
unloaded), the cassette controls will be
grayed out so you cannot load a second slide
until the first is removed.
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Once the slide is on the microscope, it will be
listed in the “Current Slide on Stage” box,
and the only thing that the Slide Loader robot
can do is return it to the cassette when you
click the “Return Slide to Cassette” button.
To move the slide around while it is on the
microscope stage, you must return to the
Microscope tab to see those controls.
APPENDIX C - MICROSCOPE CONTROL
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The microscope stage controls are boxed in red in the above image. The allow you to
move the microscope stage (which holds the specimen slide) left, right, forward or
backward. You can also focus by moving the stage up and down.
You can change the objective, which gives you increased or decreased magnification, by
clicking the buttons under Objective Selection.
The Condenser control controls whether or not the Condenser lens is in the light beam.
You want to have the condenser OUT for the 4x objective, but IN for all the others.
APPENDIX D – MANIPULATING THE MICROSCOPE IMAGE
You can manipulate the microscope image by using the controls in the red boxed area
above. The White Balance should be used only if the image appears to be brown or
gray and you think you might need to adjust it (although it won’t hurt anything to click
this button).
The Normal, Negative, etc, control buttons in this area are used to display the image
slightly differently in order to highlight certain features. Here is some information from
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the Nikon website (http://www.microscopyu.com/articles/digitalimaging/digitalsight/correctingimages.html)
about these settings and when they might be used:
Normal: In this mode, the image is displayed in the natural color scheme that is observed in the microscope eyepieces (Figure 3).
For the majority of images captured with the Digital Sight system, the normal color output is the most effective mode for accurate
and effective reproduction of all specimen details.
Negative: The Negative effect displays a brightness- and color-inverted form of the image, where red, green, and blue values are
converted into their complementary colors (Figure 4). The technique is useful with specimens for which color inversion can be of
benefit in exposing subtle details, or in quantitative analysis of specimens.
Blue Black: This mode represents the black portions of the Negative image in blue, and is often useful to reveal details in
specimens having a high degree of contrast. As a special effect, the Blue Black mode can be beneficial as a presentation tool.
Black & White: This mode displays a grayscale form of the image (Figure 6). It can be effectively used for monochromatic images
such as those acquired with differential interference contrast or phase contrast techniques. In many cases, digital images destined
for publication in scientific journals must first be converted into black & white renditions of those captured in full color. The B &
W filter can often aid the microscopist in preparing images for publication or oral presentation.
Sepia: This effect is essentially a monochrome image version displayed in sepia (brownish) tones instead of grayscale (Figure
7). The Sepia mode is more likely to be utilized in general photographic applications than in microscopy, although the effect may
enhance the visibility of specimen detail in certain instances.
Auto Exposure is normally turned on, but you can turn it off if you want to play around
with the brightness of the light source and not have the microscope camera automatically
adjust, though it’s usually best to leave it turned on.
If you turn off the Auto Exposure, then some new controls appear that let you turn the
LED off or on, and also adjust the intensity of the light source. The intensity of the light
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source can be increased or decreased manually with the dial that now appears next to
the Objective control.
APPENDIX E – CAPTURING AND SAVING A MICROSCOPE IMAGE
1
2
You can capture a high-resolution image of what is currently in the field of view of the
objective by clicking the Capture Image button, which will turn bright green while it is
capturing the image. When the Capture Image light turns off, the image has been
successfully captured. After the image is captured, click View Captured Image to see the
high-resolution image (below).
After opening this image, right click on it and select “Copy”. Then paste it into a document
so you can use it later in your lab report. This is illustrated below.
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After right-clicking and selecting Copy, just open a document and right-click and select
Paste. You can either paste it directly into your lab report document or into another one
for safe-keeping until you use it later.
You can use drawing tools in your editor to annotate this image so you can show your
instructor that you knew what you were supposed to be looking for!
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APPENDIX F - CAMERA CONTROLS
Clicking the Picture-in-Picture button will open a window that shows the view from a
camera placed directly in front of the microscope. The arrow buttons allow you to swivel
the camera around so you can see whatever you want to look at in the lab. The
Camera Preset Position buttons are programmed to show you particular portions of the
apparatus. If you hover the mouse over them, a box will pop up that lists what each
position will show you (see below).
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