TISSUE IDENTIFICATION ACTIVITY Here is a list of tissue types you are responsible for in this exercise. Pictures and descriptions of these tissues can be found in the powerpoints posted to the SWIFT site. Note: Use only these tissue types in the assignment. simple squamous epithelium simple cuboidal epithelium simple columnar epithelium pseudostratified columnar epithelium stratified cuboidal epithelium stratified squamous epithelium areolar connective tissue adipose tissue dense regular connective tissue dense irregular connective tissue hyaline cartilage bone skeletal muscle cardiac muscle smooth muscle **When you identify each tissue type, label flash cards on the back. You may use the figures in the available powerpoint for reference. A. Epithelial Tissue 1. Make a list of the assigned tissues that have an apical surface (have a free edge). These are all epithelial tissues. There should be 6 when you have finished. List the 6 types of epithelial tissue here. Separate these cards from the group and mark them as epithelial tissue on the back of the card. Hint: the photo marked 2 is simple squamous epithelium (at the arrow). It is from the kidney slide. Types of Epithelial Tissue _____________________________ _____________________________ _____________________________ _____________________________ _____________________________ _____________________________ 2. Remember: Epithelial tissue cells have three different shapes - squamous, or flat, cuboidal and columnar. Most epithelia have either one layer and are called simple, or more than one layer and are called stratified. Thus, most epithelia have a two-part name. For example, simple squamous means one layer of flat cells, stratified cuboidal means several layers of cube-shaped cells. There are exceptions. Sometimes an epithelium looks stratified, but is actually one layer of cells. The term for this is pseudostratified. Pseudostratified epithelial cells are columnar. List the 4 epithelia from your list above that have one layer of cells, and indicate the cell shape. Try to do this without peeking at your labels. Put their picture cards together in one pile. Be careful, one is tricky! _____________________________________ ____________________ cell shape ___________________ cell shape ___________________ cell shape _____________________ cell shape ______________________________________ ______________________________________ ____________________________________ √ Check your work. There should be one each of squamous and cuboidal, and two columnar epithelia. 3. List the 2 epithelia with more than one layer of cells, and indicate the cell shape at the apical surface. These cards will be in a separate pile. ____________________________________ _____________________ cell shape at apical surface ____________________________________ _____________________ cell shape at apical surface B. Connective and Muscle Tissues Read this carefully before you begin. Now look at the nine remaining cards with pictures of the tissues. Make a list of the assigned tissues that have a large amount of extracellular matrix. These are all examples of connective tissue. If the description on the powerpoint tissue image mentions fibroblasts, gel-like matrix, firm matrix, hard calcified matrix, collagen, elastin, or fibers other than muscle fibers, the tissue has a matrix, but in one example the matrix is sparse. There should be 5 when you have finished (all examples of connective tissue). Sort these out into a group called Connective Tissue with large amount of matrix. If you have 6 you have one too many! Be careful, there is a connective tissue example that does not fit here. Large amount of matrix is the key. 1. a. Connective Tissues with a large amount of matrix ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________ b. List the tissues named above that have visible fibers in the matrix (outside the cell). The word visible is important here. In some cases the fibers are stained pink, in others they are dark purple. In all cases they are outside the cells. Separate these 3 cards from the group of connective tissue figures, and write the tissue types here. Label the pile Connective Tissue - visible fibers. _____________________________________ _____________________________________ _____________________________________ c. Look carefully at the 3 tissues with visible fibers in the matrix. Distinguish among the three tissue types by describing how the fiber arrangement looks different to you. Tissue____________________________ Fiber_______________________________ Arrangement Tissue____________________________ Fiber_______________________________ Arrangement Tissue____________________________ Fiber_______________________________ Arrangement d. Which tissue with a large amount of matrix has a matrix described as amorphous? Separate it out and write its name here. __________________________________ e. Which tissue with a large amount of matrix has a matrix with a pattern organized around central canals (routes for blood vessels)? Separate it out and put its name here. __________________________________ 2. Tissues that are not epithelial tissue and do not have a large amount of extracellular matrix (includes both a type of connective tissue and muscle tissue.) Now look at the four remaining pictures that have not yet been sorted out. Which tissue has a sparse matrix and many large cells? This is a type of connective tissue that does not have a large amount of matrix between the cells. Write its name here. _________________________ Describe the appearance of this tissue. What does it look like to you? The remaining three tissue types are all muscle tissue and all have myofilaments (strands of muscle protein) inside the cell. Look carefully at these three tissues. Distinguish among the three muscle types based on things you can observe. This should include things like number of nuclei per cell, striations, branching cells, intercalated discs. Label these three pictures Muscle. Cardiac Muscle Observations_____________________________________________________________ ______________________________________________________________________ Skeletal Muscle Observations_____________________________________________________________ _______________________________________________________________________ Smooth Muscle Observations_____________________________________________________________ _______________________________________________________________________ You have now begun to sort out the tissues based on things that can be seen under the microscope. These are features that will be useful to you as you use the microscope to identify tissues on prepared slides. √ Check your work! You should have a pile of 6 pictures labeled Epithelial Tissue. Four of the pictures are simple and two are stratified epithelia. You should have a pile of 5 pictures labeled Connective Tissue – large amount of matrix. 3 of these are in a pile marked visible fibers. One is amorphous, one has central canals. You should have a picture of a type of Connective Tissue with sparse matrix. You should have a pile of 3 pictures labeled muscle. If you have not already done so, at this point your should completely identify the tissue on your reference card (ie: simple squamous epithelial tissue, hyaline cartilage, etc) Directions for Creating a Dichotomous Key Using the information you have added to the activity sheet, develop a dichotomous key in flowchart format to use in lab. Short exercise on how to make a dichotomous key. You can do this in pairs or tables. 1. Prepare a draft of a dichotomous key. The rules are simple. a. The question asked can have only yes or no as an answer. b. The question should separate out one or several of the tissues from the whole group. c. Continue asking questions until each tissue type is standing alone at the end of the flow chart. d. Use the sheet provided on the next page as a starting point--start with the question "Is there an apical surface?" The answer is either yes (Epithelial Tissue) or no (Connective or Muscle Tissue in this exercise). Ask the question and draw a line for Yes and a line for No e. Use the cards in your pile labeled Epithelial Tissue. Now separate the cards into simple and stratified epithelium by asking the question “Is it simple”? The answer is either yes (4 cards) or no (2 cards) f. Look at the pile of 4 cards. These are all simple epithelia. Ask a question about cell shape to do the next sort (keep track of these questions on your dichotomous key)--you have already done some of this work as your sorted the tissues earlier. Continue asking questions until each of the 4 tissues is alone at the end of a sort. Name each tissue at the end of the sort. g. Go back to the remaining 2 cards. These are not simple so are in the “no” column. Ask a question about cell shape to separate the 2 tissue types. Name each tissue at the end of the sort. h. Now put away the Epithelial Tissue cards and look at the cards from B. on your worksheet (Connective and Muscle Tissues). These 9 cards are in the “no” pile from the first question you asked. Follow the questions you asked on your worksheet to write sorting questions for these 9 tissue types. Name each tissue at the end of the sort. Hint: the first thing you did was separate tissues with a large amount of matrix (5) from the other tissues (4). Use the piles you have already created to help you do your sort. Note: The questions do not have to be technical in every case. You are basing your decisions on what the tissue looks like under the microscope. Students in the past have referred to "owl eyes", "tree rings", "bubbles" etc. in their questions. You are finished when all 15 tissue types have been sorted out and are alone at the end of a branch of the flow chart or key. Day 2 Using A Key to Identify Unknown Tissues 1. You can use your key to identify the tissues on the following slides. If it is unhelpful, you may want to consider revisions--you will be able to use your dichotomous key on the lab practicum section of the tissues exam (!!!), so you really want to make sure that you create a solid tool. 2. Each slide contains more than one tissue type. See how many you can identify on each slide. In your journal. clearly describe how you used your key to come to your conclusions about the tissue types. Make sure you record the number of each slide you assess. Use the observation sheet (attached to the end of the packet) as a template for your notes. For each tissue type, the observation should include: a. The name of the tissue and its description (you can reference the ppt if needed). b. A pencil drawing of what you observed. Color is preferred, but not required. The figure should be labeled, indicating characteristics of the tissue you described. For epithelial tissue, label nuclei, epithelial cells (including cell shape), underlying connective tissue, apical surface and basal surface. For connective tissue, label cells or cell nuclei, matrix, fibers (if applicable) For muscle tissue, label nuclei, striations (if applicable), intercalated discs (if applicable), branched cells (if applicable). Tissue Identification Sheet Name __________________________ Unknown Tissue Slide # __________ Tissue Type 1 _____________________________ Pathway to this decision marked clearly in color on the attached key. Tissue Description (from the lab manual): Labeled drawing of what you observed (in pencil or colored pencil). I must be able to recognize the tissue from your drawing. Do not copy figures in the text. Use the 10X or 40X lens. For epithelial tissue, label nuclei, epithelial cells (including cell shape), underlying connective tissue, apical surface and basal surface. For connective tissue, label cells or cell nuclei, matrix, fibers (if applicable), lacunae (if applicable). For muscle tissue, label nuclei, striations (if applicable), intercalated discs (if applicable), branched cells (if applicable).