Module 3 Lesson 1 - 4 (Lab)

Lab - Examining Gonads and Gametes

Introduction

Although the testes and ovaries are different structures, they serve the same two basic functions:

• development of gametes

• secretion of sex hormones

In this investigation, you will compare ovarian and testicular tissues using microscopy images (scientific term for objects viewed by a microscope) provided in an effort to identify the supporting structures that help develop the egg and sperm cells.

This lab is similar to that on page 483 of the textbook. However, because you may not have a microscope, the microscope slides are provided for you. The procedure has been rewritten to guide you through the lab using the microscopic images.

In this lesson, you will be completing Part 1: Testicular Tissue. Part 2: Ovarian Tissue is completed in the next lesson. Complete the drawings when instructed to do so as you progress through this lab.

Problem

How do the structures of testicular and ovarian tissues relate to their biological functions?

Materials

• blank paper
  
• pencil
  
• microscopy images of testis, 100X, 200X, 400X (provided below)
  

Procedure

Part 1 — Testicular Tissue

1. View the microscopy and other model images of the testes below. Where the magnification power is provided, give attention to it.


2. Read "Appendix D: Review of Biological Drawings" on page 759 of the textbook. Follow the instructions given when making the biological drawings requested in this lab.


3. Use the following image to study the internal structure of the testes.



 
SEER Training Modules, Reproductuve System. U. S. National Institutes of Health, National Cancer Institute. 31/05/2020 <https://training.seer.cancer.gov/>.





4. Examine the microscopy images provided below. Look for several circular structures. These are the seminiferous tubules. Try to identify the following cells in the images: seminiferous tubule wall, spermatogonia, spermatocytes, spermatids and spermatozoa or mature sperm cells, Sertoli cells, and interstitial cells.



Microscope image of a cross-section of a mouse seminiferous tubule at 100X magnification. US Department of Health and Human Services.  Public Domain


Microscope image of a cross-section of a mouse seminiferous tubule at 400X magnification. US Department of Health and Human Services. Public Domain. 



5. Draw a diagram of the specimen as it appears under the highest power magnification (400X). Label the following cells in your drawing: seminiferous tubule wall, spermatogonia, spermatocytes, spermatids and spermatozoa, Sertoli cells, and interstitial cells. Save your drawing for future study.

Check Your Work.

Self-Check

1. Write short descriptions of each, summarizing their functions:
   1. vas deferens
   2. epididymis


2. List the organs and glands that contribute to the components of semen.
   


3. Describe briefly the structures of a sperm cell. How does the structure of the cell relate to its function?