A&P 1 Histology Lab Week 1 In-lab Guide Epithelial Tissue ID: Stratified Squamous Tissue & Microscope Use NOTE: if you have had microbiology, or some other college-level course that uses a microscope, and you feel comfortable with a microscope, you can skip this and use the alternative Pre-lab. If you have not had a class such as this, I encourage you to get a person in your group who has! I do not care about your ability to use a microscope! Please move through this as quickly as you can! Have one person talk through the guide, while another person works the scope. Pick the person with the most experience to operate your scope. I do not care about your ability to use a microscope. Make sure everyone in your group looks into the microscope when I direct it! I will be walking around the room, helping you. If there are very few students with experience with microscopes, I will often read these instructions to you while you are working. This moves us along faster!
Step 1. ID Stratified Squamous Tissues, and learn some important lessons about microscopes, pointers, and tissue slides. Please move through this as quickly as you can! Have one person talk through the numbered steps, while another person works the scope. Pick the person with the most experience to operate your scope. I do not care about your ability to use a microscope. Remember: Your goal is to get to high power as quick as you can! DO NOT study intermediate steps! The lab guides will give you images that show you how things should look at each step. Move quickly. We will do a group exercise up on the screen after everyone has gotten through to the end of epithelial tissues: psueudostratified. You have 1 hour to get there! To help you I will be the navigator for the first tissue: Stratified Squamosal. Then, you will open the next lab guide, which covers simple squamosal. The last guide takes you through cuboidal and columnar.
#1 You will be working in groups of 3 or 4. Here s a job for each person to get ready: 1. Select a person to be in charge of using the microscope. It should be a person experienced with microscope usage. Now, do this: 2. Choose someone to read the instructions in the lab guide to the person working the microscope. This will be the navigator. 3. A third person is in charge of the images in the lab or lecture book. 1. Send the navigator to go get a slide that says Esophagus. Set it on your desk. 2. Have someone else open a lab book or lecture book to an image showing you stratified squamous. Use the index! Look in the HISTOLOGY chapter. 3. After reading this paragraph, the person in charge of the microscope should go get a microscope: Always grab a microscope by its handle and base. Always put it away when you done, making sure the handle is facing outward! The accompanying image is showing you how to carry one. Be careful they are heavy! We keep our power cords in labeled drawers around the room. Get one of the cords & plug in your microscope. Don t turn it on yet.
#2 As a group, find these parts on your scope: On/off switch, and the knob that controls light intensity Ocular & objective lens The stage, & the knobs that control the movement of the stage Course focus knob Fine focus knob Depending on exactly which type of microscope we have in the room, the Off/On button and light intensity knob might be in a different spot. Notice that the objective lenses can be changed by rotating them. Always make sure the objective lenses are set on the lowest power (the objective lens marked 4x ). This is called scanning power, because you use it to scan around. How will you scan around? Most stages have knobs attached to them that move the stage up & down, right & left (not seen in Image C ). Find these knobs. Yours might look different. the Off/On button and light intensity knob might be in a different spot! What idiot decided - means on??
#3 OK, turn the scope on. But read below, first. Believe it or not, I encourage students to look into a microscope with just one eye, placing your left eye on the right eyepiece, or vice a versa. It makes focusing MUCH easier! (I know, I know other science teachers tell you to keep both eyes open, but that is silly unless you are going to become a scientist. I keep one eye closed! The truth is they usually do, too!) Another thing if you wear glasses, take them off. If you do not, you will not put your eye against the lens, leaving a gap so you won t scratch your glasses. You will always struggle with focusing. And that eyepiece is a much better lens than your glasses, so you will make up for it when you focus! Look in one eyepiece with just one eye!!!! Now look in the other eyepiece. Notice that there is a pointer in one eyepiece only. * Sometimes it is on the left, sometimes on the right. So if you ever are asked to ID something at the pointer, and you do not see a pointer: open your other eye! Duh! or or
#4 Make sure you objective lens POINTING DOWN is 4x. This is 40x total magnification.or scanning power. Clip the slide onto the stage. Look and make sure your tissue is under the objective lens if it is not, move the tray using the knobs until it is! Look in and focus, using the course focus knob to get it close to focus, then the fine focus knob in order to get the edges as crisp as you can. Review these terms from the Microscopy lab while looking at the accompanying image: Please realize that when you go to high power, you move to the TIP OF THE POINTER! Yours will look different. It might be upside down, or the lumen might be to the side! Low Power (Scanning power) Field of view Total magnification Scanning power Parfocal
#5 Rotate the objective lenses to the 10x (100x total magnification). You are now 100 times closer. Please realize that when you go to high power, you move to the TIP OF THE POINTER! The truth is, this low magnification is fine for identifying this tissue. We are next to the lumen, and there are several layers of cells (notice how far away the basement membrane is from the lumen). And we can see the submucosa. But If you are inexperienced at looking at slides, you probably aren t sure what a cell is yet, let alone the basement membranes, right? Fine focus it again. Don t even think about touching the big knob, or you ll break the slide!! Get your pointer close to where it is in this image. How about now? Does your brain know what a cell is yet? Let s move on and make sure. Medium Power
#6 Rotate the objective lenses to the 40x (400x total magnification). You are now 400 times closer. Re-focus with the fine focus only! The cells are shaped like a cat s eye. The nuclei stain dark. Some cells are missing nuclei (they might have popped out when they made the slide! The basement membrane is dark and wavy! Make sure everyone in your group knows what a cell is! TIP! Draw what you think a cell looks like! Make sure everyone in your group agrees! Remember I told you, in the videos, that the cells can look different down by the basement membrane than they do near the surface! High Power
#8 Now, a magic trick! Go back to the previous magnification. Re-focus. Look! You can still see cells! Now go to the lowest scanning power. You can still see the cells (sort of)! See the obvious basement membrane, separating the mucosa from the submucosa? This is very typical of this tissue More importantly: you do not have to see the cells to know what type of tissue it is! You may be tested on this tissue at 100X or 400X. In the videos, I told you to come up with a descriptor term for each slide. Take out a clean piece of paper and label it Stratified squamous epithelium. Make a drawing of the tissue, if you d like, but that is time consuming, and often will not help unless you are really having a hard time seeing what a cell is. You can still see cells! For each tissue, write down your Descriptor Term and the magnification you need to study. Under that, write down some representative locations for this tissue. If your instructor mentioned any, make sure you write them down! As I mentioned, now go through the other guides. The last 20 minutes of lab, we will look at some google image searches. BEGIN!