Question about memorizing numbers

Just wanted to share this question and answer with you all, since I’m sure there are other people wondering the same thing.

Q. Do we need to know the specific percentages of everything in the blood lecture? For example, the percentage of water in the red blood cell cytoplasm, and the percentage of each protein within plasma?

A. Good questions! No – I don’t want you to memorize specific numbers. But I would like you to know the relative amounts of things. For example:

  1. For red blood cell contents: the most abundant substance inside red cells is water.
  2. For plasma proteins: albumin is the most common protein in the plasma.
  3. For the number of each type of white blood cell in the blood: Neutrophils are the most common/numerous; lymphocytes are the second most common, monocytes are the third most common, eosinophils are the fourth most common, and basophils are the least common.

The beauty of lymph

We talked in class today about lymph, which is the clear fluid that flows through lymphatic vessels and lymph nodes and eventually returns to the blood. I mentioned that the etymology of the word lymph was beautiful but I didn’t want to take up too much class time talking about it – so I’m posting the story here.

How did lymph get its name? It turns out that lymph is a combination of a couple different words: the Latin lumpa, meaning water, and the Greek nymphe, meaning spring goddess. The resulting word – lympha in Latin, lymphe in French – means clear water or a goddess of water.

I just love this so much. First of all, lumpa sounds gross, and I wouldn’t want to have to deal with that word all the time. Second, we now have an accurate description (lymph does look like clear water) overlaid with a lovely, delicate image (spring water goddess). I mean, what more could you want?

Now every time I hear lymph, lymphatic, or lymphocyte, my brain will conjure up something like this:

This is Persephone, the Greek goddess, bringing spring to the frozen tundra.

How neutrophils get out of blood vessels – it’s crazy!

First, a disclaimer: I won’t be testing you on the stuff in this post. I just want to show it to you because it’s so incredible! With that out of the way, let’s take a look at some neutrophil craziness.

In order for neutrophils to fight infection or help clean up after an injury, they need to get out of the blood and into the affected tissue. The name for this process is “recruitment,” and it consists of a series of five steps. Most of these steps are pretty straightforward, but one of them – diapedesis, or migration through the vessel wall – looks insanely difficult and painful. If neutrophils had nerves. Which they don’t. But still.

By the way, diapedesis comes from the Greek dia (through or across), the Latin ped (foot), and the Greek esis (a suffix used to form nouns of action or process). So diapedesis is the process of neutrophils poking their tiny feet through the blood vessel wall! OH MY GOSH that makes me so happy. 

Here’s an electron micrograph of a neutrophil undergoing diapedesis. Before you scroll down any further, take a good look at the photo. The neutrophil is the cell in the middle…and it’s sucking its gut in and squeezing between two endothelial cells. Can you figure out which side is the tissue side and which side is the interior of the blood vessel? There’s a labeled figure at the bottom of this post when you’re ready.

Here are the five steps:

  1. Margination. Neutrophils stick to the inside of the vessel walls.
  2. Rolling. This is what it sounds like: the neutrophils adhere briefly to the endothelium, detach, adhere again, detach, etc. in a rolling fashion until they find a good stopping point.
  3. Adhesion. Then the neutrophils stick firmly to the endothelium.
  4. Diapedesis. Here’s the craziness! The neutrophils have to squeeze between the endothelial cells to get out into tissues. This is just nuts, because neutrophils are MUCH MUCH larger than the tiny little gap between adjacent endothelial cells. So they really have to suck it in, and slowly squeeze themselves through (without rupturing their cell walls or anything inside, by the way). How the heck do they do this?? They are so totally committed to fighting those bacterial that they will literally squeeze themselves through a tiny gap to get out of the vessel and into the tissue. Impressive. 
  5. Migration. Once they’re on the other side, the neutrophils shake it off, and migrate through the tissue to the exact place they are needed.

I’m exhausted just thinking about it. Good job, little neutrophils!! 

Here’s the same EM with labels.

Results for Exam 1 are in!

Exam 1 is now closed! Everyone completed the exam, and you guys did really well!! Before making adjustments (see below), the mean was 91%. Nice job!!

When I went through the question metrics, I found a couple questions that didn’t perform too well – so I’d like to show you those questions, explain what went wrong, and tell you what I’m going to do to adjust the scores.

The first one is question 25:

Which of the following best describes the morphology of cardiac muscle cells?
A. Long, unbranched cells with multiple peripheral nuclei
B. Short, branched, striated cells
C. Spindle-shaped, branched, striated cells
D. Long, branched, striated cells
E. Spindle-shaped, unbranched, non-striated cells

The correct answer is B. 60% of the class answered the question correctly, but over 30% chose D. This was a new question that I just wrote this year, and new questions sometimes don’t perform well. Although I check and double check the stem and distractors, I don’t always see the question the way you guys do. That seems to be the case this time; enough of you chose D to make me think that this was not a very good question.

I don’t want to throw the question out (that would punish the people that got it right), and I also don’t want to accept D as correct (because it’s not correct). So in these cases, I feel the fairest thing is to give everyone one extra point. That way, the people who answered incorrectly get that point back, and the people who answered correctly get an extra point (so they get recognized for answering the question correctly). There are so many different ways to handle this type of question – but to me, this way seems the most fair, so that’s what I tend to do most of the time.

The second one is question 37:

Proteoglycans are composed of a ___ core with a bunch of attached ___.
A. Carbohydrate/proteins
B. Glycosaminoglycans/carbohydrates
C. Glycosaminoglycans/proteins
D. Protein/carbohydrates
E. Protein/glycosaminoglycans

The correct answer is E. Only 50% of the class answered correctly (which right there is enough to make me think I didn’t explain this concept well enough in class/on the powerpoint). Most of the rest of the class answered D. So while E is still the correct answer, something about the way I explained this concept didn’t land for many of you, and as a result, you answered incorrectly. So I’m going to do the same thing for this question: add an extra point to everyone’s score.

I’ve released everyone’s results to your Examsoft student portals. That way you can see the questions you got wrong, which is an important thing to check because that way you can correct your knowledge. Also, if you chose an incorrect answer, but you feel you have a good reason for why you made that choice, email me and we can talk about it. Sometimes there is something that I didn’t think of, and in those cases, I’ll add a point to your score. Usually, though, the questions students get wrong are pretty self-explanatory; often it was something that the student didn’t cover when they were studying, or something they just forgot on exam day.

What I DON’T want is for people to be getting questions wrong because the question was confusing in some way. So if you felt that a question was confusing, I’d appreciate it if you let me know! I want to test your knowledge, not try to trick you or make you guess what I’m getting at. You wouldn’t think it would be so hard to write straightforward, good questions – but it is!

Finally, please note that the score you see from Examsoft in your student portal is the score you got before I added in the extra points. I’ve entered the corrected scores on Canvas, and that’s the place you should check for your actual, accurate score.

Sorry for the length of this post! I just want to explain these things at the beginning of our time together so that you know how I handle exam questions for all of our courses that we’ll have together.

As always, if you have any questions, please drop me an email.

An apology and an explanation

I intended to post the exam question breakdown, the sample exam questions, and the other information about the exam over the weekend, but that didn’t happen – and I want to apologize and explain why I didn’t get those things done earlier. A very close friend of mine, who had been sick for quite a while, and suffering a lot the past few weeks, finally passed away – and although we knew it was coming, that didn’t seem to make it any easier when it finally happened.

I have a handful of student emails from the past few days in my inbox, and I am sorry I haven’t gotten to them yet. I have two meetings in the morning that I can’t miss – but I will answer those emails, and any others that come in, as soon as I’m free.

Thank you for your patience.

Information about Exam 1

This post contains specifics and logistics for our first exam in General Histology (DDS 6214). Please email me if you have any questions not answered here! I’ll send out an email with the password to the exam tomorrow night.

Start and end time

The exam is scheduled for Thursday, September 1, and you may take it any time between 12:01 am and 11:59 pm that day. Once you open the exam you have two hours to complete the exam. All submissions must be uploaded by 11:59 pm on Thursday in order to receive a grade.

Classroom availability

Our classroom should be open and available from 1:00 – 3:00 pm tomorrow, if you want to take the exam at that time in our classroom. I’d suggest that if there are several people in the the room, please try to space yourself out well so there’s no way anyone (including ExamMonitor) can suggest the possibility of you looking at someone else’s computer 🙂


I aim for roughly 5 questions per lecture hour on our exams (in this class and in our future classes). For this exam, the Intro to Histology lecture was quite short, so I only have two questions on that lecture. Here’s the full breakdown by lecture:

Intro to Histology: 2 questions
Embryology: 5 questions
Epithelial Tissue: 10 questions
Muscle Tissue: 10 questions
Nervous Tissue: 5 questions
Connective Tissue: 5 questions
Cartilage and Bone: 10 questions

Please take a look at the Sample Exam Questions post to get an idea of how I write questions. There will not be any tissue microscopic images on the exam, but as I mentioned in class, there will be an electron micrograph image of the sarcomere on the exam. Questions 17 and 18 in the Exam 1 Review Kahoot, and question 4 in the Sample Exam Questions post show this image and give you an idea of the kinds of questions I might ask on the exam.

Examplify Information

You will take this exam using Examplify installed on your PC/Macintosh laptop or desktop computer. If Examplify is currently installed, it may require an update and computer restart before the exam. If it is not installed, you should download and install the most up-to-date version of Examplify before the exam.

This exam will be remotely proctored using ExamID and ExamMonitor. This means you will take a photo of yourself at the start of the exam for identity verification and you will be recorded during the exam. So only laptops/desktops with a working camera & microphone and Chrome or Firefox browsers can be used to complete the exam. Please note, iPads are not compatible with the ExamMonitor software and may not be used for this exam.

No scratch paper is allowed during the exam – but I have enabled the digital notepad feature within Examplify, so you can use that if that helps. Also, just a reminder that using electronic devices (phones, tablets, smart watches, headphones) is not allowed while taking the exam.

If you experience any anomalies while taking the exam (examples include barking dogs, interruption by a family member, etc.) please email me at after completing the exam to let me know.

Here’s a quick troubleshooting guide for Examplify for your reference.


After you take the exam, you will immediately receive your raw score. Final scores will be posted to your ExamSoft Student Portal and Canvas after I’ve reviewed the exam metrics. I plan to do that on Friday morning.


If you have any questions about the exam please feel free to email me any time tomorrow. I’ll be checking my email frequently so I will be able to respond quickly.

Sample exam questions

I’d like to give you a heads up on the way I write exam questions, so you’re better prepared for this first exam.

Exam questions should test your knowledge (obviously). You shouldn’t get a question wrong because it was confusing, or because it intentionally led you down the wrong path. When I write questions, I try to be as straightforward and clear as possible, so you understand what the question is asking you. And I don’t try to trick you into picking the wrong answer.

So if you look at a question and you know the answer right away, that’s okay! Don’t worry that you missed some sort of trick, or that the question can’t possibly be that simple.

Here are some examples of typical exam questions:

1. In general, what happens during the second phase of the embryonic period?
A. Cells proliferate and migrate
B. Internal and external structures begin to differentiate
C. Organs grow and mature
D. Organs reach their maximum size

2. Which type of intercellular junction attaches epithelial cells to the basal lamina?
A. Zonula occludens (tight junction)
B. Zonula adherens (belt desmosome)
C. Macula adherens (spot desmosome)
D. Gap junction
E. Hemidesmosome

3. What would you call epithelium composed of one layer of cells that are much taller than they are wide?
A. Simple squamous
B. Simple columnar
C. Stratified squamous
D. Stratified cuboidal
E. Pseudostratified columnar


Question 4 refers to the electron micrograph above, which shows a sarcomere in its relaxed state.

4. Which letter (and corresponding line) marks a region that contains ONLY myosin filaments?
A. A
B. B
C. C
D. D

5. On H & E staining, which type of connective tissue proper is composed of abundant ground substance, scattered cells, and some thin fibers?
A. Dense irregular connective tissue
B. Dense regular connective tissue
C. Loose areolar connective tissue
D. Loose reticular connective tissue

6. Which glial cell myelinates axons in the central nervous system?
A. Astrocyte
B. Ependymal cell
C. Microglial cell
D. Oligodendrocyte
E. Schwann cell


Scroll down for the answers!










1. B
2. E
3. B
4. B
5. C
6. D

Hyaluronic acid products!

On Monday, in our connective tissue lecture, we talked about hyaluronic acid, this incredibly huge glycosaminoglycan (over a million daltons – wow!) that does all kinds of things, including holding up to 1000 times its weight in water.

We talked about how it’s used in dermal fillers like Restylane and Juvederm. And I mentioned that old formulations of topical hyaluronic acid had just plain old huge hyaluronic acid molecules in them (so they just sat on top of the skin and – at most – did a little moisturizing) – but now, there are products that contain several different sizes of hyaluronic acid molecules (some even have HA packed into nanoparticles), so they can actually permeate the skin and add some resiliency. Nice!

So I thought I’d share some information on topical hyaluronic acid products here in case you’re interested.

First, here’s a great overview article on topical hyaluronic acid products from this great website called Into the Gloss. You may already know this, but in case you don’t: the creator of Into the Gloss, Emily Weiss, started a skin care and beauty brand called Glossier several years ago. The products are so good, and so reasonably priced, that they very quickly gathered a cult following – and in 2019, Glossier officially became a unicorn (a business valued at over 1 billion dollars).

Anyway – Glossier has a great hyaluronic acid product called Super Bounce that’s only $29. I was talking with a few students after class and one mentioned The Ordinary’s hyaluronic acid serum  which is also really good, and only $13.50 (they have a ton of really high quality products at incredible prices – no idea how they do it!). If you have a favorite, email me, and I’ll post it here! Who knew histology could be so practical?!

Question about the 9 + 2 arrangement of the axoneme

Q. Why are the 2 central microtubules not a pair but the 9 pairs on the outside are considered pairs (instead of 18 microtubules) in the cilia? Is that because they are of a different type?

A. Thank you for bringing this up! It is confusing that we call this a “9+2” arrangement when it looks like there are 9 pairs of microtubules around the outside, and one pair of microtubules in the middle! Seems like it should be either “9+1” or “18+2.” There’s a good explanation, though. Here’s a diagram of an axoneme – we’ll talk about the “2” part and the “9” part separately below.

The “2” part of the axoneme
The two microtubules in the center of the axoneme are totally separate from each other. So they can be considered to be 2 separate, independent units.

The “9” part of the axoneme
The 18 microtubules around the outside are bound together, two at a time – so they can be thought of as 9 separate, independent units.

It turns out that in each of these 9 units, one of the microtubules is incomplete. If you look at the microtubules circled in red, you can kind of see that the top one looks round, and the bottom one looks like it’s not quite round, and has sort of just latched on to the top one. The bottom one is actually not a fully-formed microtubule (if you pulled the two apart, the top one would be round, and the bottom one would look like a C-shaped structure). So we really shouldn’t even call these guys “pairs” since they don’t consist of two fully-formed microtubules. The official name is “doublet” – and that is a little better than “pair,” I guess.

Questions about glands

Here are some great questions about glandular cells!

Q. I wanted to clear up some confusion I have about exocrine glands and glandular cells types. I understand that there are 3 different glands; merocrine, holocrine, and apocrine. Within these glands with specific processes of secretion, there are different kinds of glandular epithelial cells; ion-transporting, serous secretory, mucous secretory, neuroendocrine, and myoepithelial cells. Is this correct? Continue reading