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>BIOL 3

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Histology

Written Assignment

Completion Deadline: Saturday, March 20, 202

1

by 11:

5

9 PM

Late submissions are subject to a 10% penalty per day and will not be accepted after 2 days. Technical trouble is no excuse, do not wait until the last minute to complete this assignment!

Assignment. Histology, as do all life sciences, is constraint by physical realities. Physical realties such as osmosis, diffusion, tensile and compression strength, and thermoregulation to name just a few, can be modeled by mathematical approaches such as surface-to-volume ratios (see your very first Reading of the semester). Indeed, we can predict many structural properties of tissues through mathematical modeling. In this Written Assignment, we will (I) experimentally derive a surface folding-thickness relationship; (II) plot this relationship graphically; (III) develop two histological examples where this surface folding-thickness relationship is crucial; and (IV) identify pathologies that may interrupt an optimum surface folding-thickness relationship.

This assignment will force you out of your comfort zone (that is where learning is most effective!) and will leave you frustrated at times. However, if you follow my instructions below, document what you did well, and provide rational and well-structured explanations for your conclusions, you will be able to achieve a high grade for this assignment somewhat independent of whether you arrived at the correct conclusions– all you need to do is follow the instructions, be self-critical and focus on details!

The assignment should contain
four well-defined components
:

(I) Surface Folding-Thickness Experimental Design

As you have probably seen in countless images of the brain – it is a deeply folded structure. We will take our inspiration from the folding of the brain and actually execute it as an experiment to get real data on how the amount of folding of a surface differs based on the thickness of the structure. You need a pile of cheap paper (old newspapers, recycled paper, old phone book) – all pages need to be of similar size and thickness. Now line up a stack of paper and strongly bunch it up (as a unit) in your hand to create a paper ball. Repeat with stacks of paper of different height (i.e., one sheet,

2 sheets

, 3 sheets, 5 sheets, 8 sheets, etc. – you design the experiment). Unfurl each paper ball and use a marker to highlight every fold on the top sheet (=surface). PLEASE WRITE ON THE TOP OF THE MARKED PAPER THE DATE OF YOUR EXPERIMENT (for example: March 12, 2021) Measure all marked folds on your paper and sum up. Repeat for each ball.
For the assignment, I want you to write a short experimental design
where you identify all aspects of your experiment so that someone else could repeat it and get the same result: for example, you need to describe the paper size and type (As best as you can), how many papers you stacked for each ball, how you defined and measured a fold, etc. Include any quality assurance (replications, controls, etc.) you used to make sure you got good data! I also want you to place the stacks of paper (after you balled them up, smoothened them out and marked the folds on each top layer) next to each other and
take a picture to include in the assignment after the description of the experimental design
(use your cell phone or similar camera to take the picture – it does not have to be fancy, but I want to see the stacks of paper and the marked folds – if you have more information to include in the picture that is great). Make sure the marked date is visible in the photograph! I would expect that it will take you approximately 300 words to describe your experimental design.

(II) Plot the Results of Your Experiment

For this part of your written assignment (to follow the picture of the paper stacks) you have to produce a couple of components: a
Table
with your results from the experiment (see a possible example below) and
two

Graphs
that visually show the relationship between thickness and amount of folding. Graph 1 plots paper thickness (# of sheets) against the sum of folds you have measured on the top page of each paper stack (in other words, each paper ball you created in your experiment becomes a data point in the graph). Graph 2 plots paper thickness (# of sheets) against the length of folds divided by the surface area (i.e., the unit would be length/area – for example: cm/cm2). Graph 2 conveys the same information as Graph 1 but by normalizing for surface area is more broadly applicable. You can make those graphs in Microsoft Excel or another program and import them into your assignment or you can draw them by hand, take a photograph and import that into your Written Assignment – any way that is easiest for you works for me as long as I can see your data in graphical formats. End this section by
describing the relationship you uncovered in a couple of sentences
.

Here is an
example
on how the Table could like (however, you may have a better idea of how to design your table and that is just fine (:

1

2

(III) Histological Examples of Surface Folding-Thickness Relationship

Now that you have a better sense on how surface folding is affected by the thickness of a tissue, go ahead and come up with
two examples from histology where surface folding is important
(describe how it is important – what function is served by the folding) and which tissues contribute to the folding. This section is important and you should develop each of the two examples in some detail (I would expect at least 300-500 words for this section of the assignment)

(IV) Pathologies that Disrupt Surface Folding-Thickness Relationship

Now that you have experimentally derived the relationship between surface folding and the thickness of the tissue and have described two histological examples of its importance, it is time to think about what can go wrong! Identify two pathologies (i.e., abnormal changes to tissues) that would alter the normal/healthy surface folding-thickness relationship and therefore the folding capacity of the tissue. Maybe one pathology for each of the examples from Section III or some other pathologies. I expect you to describe the pathology (what is wrong?) what causes it, how it would affect the surface folding-thickness relationship, and finally what biological function would be hindered by this pathology. This is another important section and you should develop each of the two pathologies in some detail (I would expect at least 300-500 words for this section of the assignment).

Please cite this article and any other source you use at the end of your assignment.

Bonus (1pt): Many histological structures are named after scientists (Golgi Apparatus for example is named after Mr. Golgi – can’t use this example for the bonus (. Identify a histological structure named after a person and briefly (2-3 sentences) describe how this person was. You get a second bonus point if you are the only student who came up with this particular histological structure (originality point!)

Practical Considerations

· Scientific writing style should be applied throughout the text and can be modeled after the research article you have read – any citation/reference style is fine as long as it is consistent.

· Clarity, precision, and attention to detail is crucial to a good research article and will be assessed in the evaluation.

· A clear structure and good flow are essential.

· Review the rules set forth regarding plagiarism (see previous handout and exercise).

· ALL assignments will be checked for plagiarism and any cases of plagiarisms will result in a zero grade for the assignment.

I will use the following questions to grade your essays, keep them in mind as you write your essay:

· Does the assignment have mechanical problems?

· Does the assignment have a clear structure and good flow? Did the student follow the instructions for the assignment?

· Are all four sections fully developed?

· Does the assignment contain the Picture of the unfolded paper balls, the Table with the measurements, two graphs with the Surface Folding-Thickness relationship?

Do not:

– wait until the last minute to complete portions of your assignment.

– expect any consideration from me if you have “technical” problems on the day your assignment is due – you had plenty of time prior to address problems with me.

– write your assignment in haste – this is an upper division writing assignment, do not waste your peers with a last-minute submission of low quality!

– do not cheat, plagiarize, or copy assignments – I WILL catch you!

Do not hesitate to contact the Write Place (308-2031) for help with your assignment – they are trained to do so and can greatly improve your writing ability!