1. Model Mania: Using 3D Models for A&P
Presented by
Elizabeth Carson
Karen Shepherd
CAST 2015

2. Importance of 3D spatial understanding
Students can have great difficulty looking at tissue with a light microscope and understanding its 3D structure

3. Tissue Types in Anatomy
Epithelial Tissue
Connective Tissue
Muscle Tissue
Nervous Tissue
Histology is typically one of the first unit that is taught in a high school anatomy and physiology class. Normally, students view microscope slides and those good at memorizing identify them correctly. Many times there is little understanding of either the scale of these tissue samples or the 3-D structure of these samples. There are four categories of tissue which are epithelial tissue, connective tissue, muscle tissue, and nervous tissue.

4. Epithelial Models
Epithelial tissue is classified by its cell shape and number of cell layers
Cell shape: Squamous, Cuboidal, Columnar
Tissue arrangement: Simple, Stratified, Pseudostratified
In constructing an epithelial tissue models, the teacher must first address how epithelial tissue is further classified. Epithelial tissue is classified by cell shape and number of cell layers. Also, remember that there are several tissue arrangements: simple, pseudostratified, and stratified. There is also transitional, but we are not going to discuss that one today.

5. Epithelial Models
How can we make the different cell shapes out of paper bag? What needs to be added to the bags to make them more representative?
Squamous
Cuboidal
Columnar
Students should each be handed three white lunch bags and a pair of scissors. They should be asked to unfold one and describe what shape they think it best models—-squamous, cubodial, or columnar? The teacher should help students identify that the open bag is would best represent a columnar cells. Then the teacher should ask students how might one use the markings on the bag to help them identify what would represent a cuboidal cell and a squamous cell. The teacher should have the students cut the additional lunch bags to represent the cubodial cell and the squamous cell.

6. Name this Tissue Simple Squamous Epithelium
I use my cell phone to take pictures of the slides in focus to show the students what they are looking for in the slide so we can practice naming tissues. I also use photos put into a power point as a practical at the end of the histology unit and during units. It decreases some of the issues with microscopes getting moved during the practical and each computer has a different form.

7. Name this Tissue
Simple Cuboidal Epithelium

8. Epithelial Tissue Arrangement
Combine “cells” to make simple squamous, cuboidal and columnar
The teacher will now divide the room into their student team. The teacher will have all the student teams stick their squamous cells together to make simple squamous tissue. Discuss the limitations of this model. Attach the model to a piece of paper that will represent the basement membrane. The teacher should discuss the “normal” color of tissue. What are some ways that tissue get color? Does simple squamous have a natural color? What is it? From where does the color come? Tissues are stained to aid in the viewing of internal structures like the nucleus. Students can look back at the slide of simple squamous epithelium and identify the cell structure that are seen. They can mark them accordingly with a purple marker. Student groups should then combine their simple cubodial cells to make simple cubodial tissue and their simple columnar cells to make simple columnar cells. Predict the function of each type of simple epithelial tissue.

9. Modeling Stratified Epithelium
Break up into groups. Each group construct a model of stratified tissue.
Labeling your model. Based on this microscope slide, what structures can you see under the microscope? Color and label those.
Student groups will decide how to make stratified epithelial tissue. Each student groups will construct a model of stratified epithelial tissue and label the parts that could be seen on the microscope slide.

10. Epithelial Models
Students should then be given a laminated image of stratified squamous tissue. They should label the location of the basement membrane. If possible, they should also draw lines between the cell membrane and determine the cell type. How many tissue layers do you seen? How does this compare to the model you just built? Do you need to revise your model?

11. Here is my picture from my slides of stratified squamous epithelium (skin) How can we use our simple epithelium models to construct this model? Do the cells look as aligned as the model? How can this be made more realistic? (smash bags to show skin) What other types of tissues are found in skin. We will continue to make more models to show a representations of the skin layers. Saves these around the room after they are constructed for review……or don’t put them together at this point but when we talk about skin, have them get their models and make their skin with them.

12. Challenge Model: How would you make pseudostratified epithelium?
Epithelial Models
Challenge Model: How would you make pseudostratified epithelium?
As a challenge or a homework assignment, the teacher can ask students how they would model pseudostratified epithelium tissue. To help them determine the cell shape and tissue arrangement, students should again identify the basement membrane and then determine the cell boundaries. What will you use to model the cilia?

13. Connective Tissue Models
Connective tissue is classified by the cells, fibers, and matrices.
Let’s look at several slides to determine how best to model these types of tissue.
Connective tissue is unlike epithelial tissue in its classification. Connective tissue is classified by its cells, fibers, and matrices. That puts all types of connective tissue into one of two categories: connective tissue proper and cartilage.

14. Connective Tissue Proper
Cells: Fibroblasts
Matrix: Mostly hylaronic acid, but there are some exceptions
Fibers: depends on the type, can be reticular, collagenous, and elastic
Connective tissue proper, for the most part, contains fibroblasts and one of three types of fibers (reticular, collagenous, elastic, or some combination of those). The matrix is typically hylaronic acid. There are some exceptions to this rule: adipose, blood, and bone are also connective tissue proper. These types of connective tissue proper have different cells and matrix.

15. One example: Areolar connective tissue
Connective Tissue Proper
Cells: Fibroblasts
Fiber: Collagenous, Reticular, and Elastic
Matrix: Hylaronic acid
In groups, we construct areolar (loose) connective tissue. We do our best to make the connective tissue look like the image provided. The cells in this model are fibroblasts which are represented by purple balloons. Areolar connective tissue has three types of fibers: collagenous, elastic, and reticular. Since collagenous fibers stain pink, they represented by pink streamers. Elastic fibers do not stain well so even though they are present, they are white. Elastic fibers are represented by white streamers. Reticular are much thinner than the other two fibers. They stain purple. They are represented by purple ribbon. Of course, the matrix is hylaronic acid, but we will not include that in the model because hylaronic acid is a liquid. Adding that component to the model would make the model messy.

16. Now make your own
Get with a partner and construct a model of your dense connective tissue.
Cells: ?
Fibers: ?
Matrix: ?
This is dense connective tissue which is the type of tissue that makes up tendons, ligaments, fascia, and aponeuroses. Look at the model that we just made. Predict the types of cells and fibers that this tissue has. How do you think the streamers that represent the fibers should be arranged so they appear “wavy?“ In my class, student groups are assigned a type of connective tissue proper of which to construct a model. Each student group presents their model to the class and we critique them. Modifications are made as needed. When the model is done, it is displayed in the room.

17. Cartilage Cells: Chrondrocytes Matrix: Chrondroitin sulfate
Fibers: Depends on the types, can be elastic, collagenous, or reticular
The cells in all types of cartilage are chrondrocytes. The matrix in all types of cartilage is chrondroitin sulfate. The difference between cartilage types is the types of fibers and the relative size of the chrondrocytes. This activity is also done over a period of two days. On the first, we discuss how cartilage differs from connective tissue proper. As a class we make an elastic cartilage model. On the second day, student groups construct the type of cartilage they have been assigned.

18. One example: Elastic cartilage
This is elastic cartilage which is the type of tissue that makes up tendons, ligaments, fascia, and aponeuroses. Pink or hot pink balloons are used to represent chrondrocytes. All cartilage has fibers, but the fibers in this type of tissue do not stain well. So, students should be able to infer that this type of cartilage has elastic fibers. White streamers should be used. Student groups are assigned a type of cartilage of which to construct a model. Each student group presents their model to the class and we critique them. Modifications are made as needed. When the model is done, it is displayed in the room.

19. I would divide up the class and have one group make elastic, one hyaline and one fibrous…..if you choose to do cartilage at all

20. Blood
Living cells (RBCs, WBCs) in a non living matrix (plasma)

21. Identify the Parts
Here’s one to try with candy or this one

22. Discuss why adipose is a connective tissue and its function

23. How could we make adipose. I was thinking balloons
How could we make adipose? I was thinking balloons. These could be saved to make a large skin model later.

24. Turning Muscle Tissue into a Muscle Organ
We construct this model before we start dissecting.
I have students construct this while lecture as well.
This activity is done when we are studying the muscular system. My students and I construct a muscle (organ) from skeletal muscle and dense connective tissue proper. In this model students use clear plastic wrap to represent the dense connective tissue and red fuzzy sticks (pipe cleaners) to represent the skeletal muscle tissue. Individual muscle fibers (one red fuzzy stick) is wrapped with a sheet of clear plastic wrap. Student teams placed their wrapped individual muscle fibers together and wrap the entire bundle with clear plastic wrap to create a fascicle. All student groups combine their fascicles and wrap them a large sheet of clear plastic wrap to create a muscle. Before the clear plastic wrap is closed shut, several long pieces of thick white yarn are added to represent the nerve tissue in that muscle (organ). Also, several long pieces of thin red yarn is added to represent the blood vessels (both veins and arteries).

25. This activity is done when we are studying the muscular system
This activity is done when we are studying the muscular system. My students and I construct a muscle (organ) from skeletal muscle and dense connective tissue proper. In this model students use clear plastic wrap to represent the dense connective tissue and red fuzzy sticks (pipe cleaners) to represent the skeletal muscle tissue. Individual muscle fibers (one red fuzzy stick) is wrapped with a sheet of clear plastic wrap. Student teams placed their wrapped individual muscle fibers together and wrap the entire bundle with clear plastic wrap to create a fascicle. All student groups combine their fascicles and wrap them a large sheet of clear plastic wrap to create a muscle. Before the clear plastic wrap is closed shut, several long pieces of thick white yarn are added to represent the nerve tissue in that muscle (organ). Also, several long pieces of thin red yarn is added to represent the blood vessels (both veins and arteries).

26. Skeletal Muscle Fibers: multinucleated contractile cells varying from less than 10–100 mcm in diameter and from less than 1 mm to several centimeters in length; the fiber consists of sarcoplasm and cross-striated myofibrils, which in turn consist of myofilaments; human skeletal muscles are a mixture of red, white, and intermediate type fibers.
Red chenille stems

27. Endomysium: delicate connective tissue sheath that encloses each muscle fiber
Each student wraps an individual red chenille stem in saran wrap to model the muscle fiber covered in an endomysium - none of the wrappings have to be perfect - you want extra left over on the ends to make a tendon

28. Perimysium: coarser fibrous membrane that sheaths or wraps several sheathed muscle fibers
Small groups of students combine their wrapped pipe cleaners to make a perimysium/fascicle

29. Fascicle: several sheathed muscle fibers wrapped by a perimysium
combine to make 3-5 fascicles per class

30. Epimysium: many fascicles bound together by a tough “overcoat” of connective tissue
Each class of students will combine their fascicles to make a specific muscle or two, depending on the size of the class. Yarn can be used (red-arteries, blue-veins, yellow-nerves) to represent the blood vessels and nerves

31. Show to students after they have constructed their muscle so they can see a cross section of what they have made

32. Tendon: cords of dense fibrous tissue attaching a muscle to a bone
Excess suran wrap at the ends of the class muscles represents the tendons which can then be attached on to the correct origin and insertion point on the skeleton

33. Nerve Tissue This is done as an independent project.
Students design a model of a nerve tissue as an independent project outside of school.
What are some things that you are doing in class?
Nerve Tissue is a part of this unit that is still under development. This is due to scientist changing ideas of the nature of nerve tissue. Normally, students make an independent model as a choose as an end of the unit assessment in the nervous system.

34. Adapted from 3-D Tissue Models Anyone Can Build by Ruth Lehmann Hutson Blue Valley High School, Randolph, KS

35. Questions?
Works Cited
All microscope images are found at: JayDoc Histoweb The University of Kansas. Date accessed April 4, 2014.
A free collection of supplemental materials is available by searching 3-D Tissue Models that anyone can build on the NSTA Learning Center.