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Utilization of Veterinarian's Spare Parts

Joan B. Radakovich



Abstract:

The following activities use organs from dogs and cats. The organs are used in the study of reproduction, embryology and the identification of cancer. These are inquiry/observation based labs. The student-group will examine a non-pregnant uterus, testicle, pregnant uterus and cancerous testicle. As a group they will record all observations, at both the gross and microscopic levels. Groups will present the information obtained to the class.

Activity Type:

  • Hands-on
  • Inquiry lab
  • Group/cooperative learning
  • Review/reinforcement

Target Audience:

  • Life Science
  • Biology
  • Anatomy and Physiology
  • Special needs (gifted, ESL)
  • Special education


Background Information

Teacher -

All organs can be obtained free from area veterinarians. Ask several to save the parts, then pickup and store in the freezer until you are ready to use. I purchase the DiffQuik staining kit through the vet. Share with the students that NO animal has lost its life for this lab. This activity purposefully lacks much structure and teacher direction. I find students have a genuine interest and stay on task without teacher reinforcement and guidance. Making a competition out of the most observations obtained for each organ has instilled additional drive. Student groups consist of 2-3 students.

Student -

Students should have general knowledge of the anatomy and physiology of reproduction and embryology.

Preparation time: The collection of organs is a year-round task for the teacher.

Class Time needed:

The observations take three class periods. A 50 minute class period is needed for observations on the non-pregnant uterus and testicle. The pregnant uterus and cancerous testicle each take a class period. Presentations and questions occupy the fourth day.

Materials (per lab group):

  • Organ #1 on Day 1 (non-pregnant uterus)
  • Organ #2 on Day 1 (testicle)
  • Organ #3 on Day 2 (pregnant uterus)
  • Organ #4 on Day 3 (cancerous testicle)
  • Dissecting tray
  • Scissors
  • Forceps
  • Probe
  • Microscope slide
  • Cover slip
  • Microscope
  • Stereoscope (or hand lens)
  • Methylene blue
  • Metric ruler
  • DiffQuik Stain Kit


Description of Activity:

Day 1

Each student group obtains a non-pregnant uterus, testicle, dissecting tray, scissors, forceps, probe, microscope slide, cover slip, microscope, stereoscope, metric ruler and methylene blue. Students examine the organs and make as many observations as possible using the equipment available. Any questions the group has are also recorded. Students are reminded that stains (like methylene blue) will sometimes help the observer see microscopic structure. If a group is finished early they are encouraged to walk around the room and observe the other groups' organs.

Day 2

Each student group obtains the same materials as on Day 1 but substitutes a pregnant uterus. The students follow the same instructions from Day 1.

Day 3

The student group obtains all materials listed. The students record observations on cancerous testicle. At this time the students are introduced to a technique for staining. An impression smear of the cancerous testicle is made. The slide is heat fixed and then stained with the DiffQuik stain kit (directions come with kit). The slide is then blotted dry and ready to observe. An oil immersion objective is best but high power will also suffice. The students make observations on cell size, shape, number of nucleoli, and number of nuclei.

Day 4

The student groups cooperatively answer the following questions and present their observations to the class. Any questions from the groups are presented to the class and collectively we try to answer them.

Questions:

  1. Identify organs 1 & 2.
  2. Identify the function for each of these organs.
  3. Where do you think your organs came from (dog/cat)? Why?
  4. Identify organ 3.
  5. Where do you think this organ cam from (dog/cat)? Why?
  6. Average gestation for a dog and cat is 63 days. How old do you think your puppies/kittens were? Why?
  7. Identify organ 4.
  8. Did you observe a discrepancy in size, shape and number of organelles in the cells from organ 4?
  9. What could possibly cause this discrepancy?


Method of Evaluation:

Give points in direct relationship with number of observations, class presentations, and answers to the questions.

Extension:

Occasionally I come across an infected uterus. I show it to the class and they are quick to identify it as a pregnant uterus. With the snip of the scissors and the oozing of pus they quickly find that looks can be deceiving. Testicles can also be used for a DNA extraction lab.


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