B141 Semen Evaluation Lab
Morphology & Concentration
Name ______Date ______
Sperm Cell Morphology Lab Instructions
In this lab experience, you are going to evaluate the semen on morphology and calculate concentration. Before beginning this lab, answer questions 1 through 3. Then prepare a slide of bull semen using the same procedure as outlined in the previous sperm motility lab. However, in this lab we are going to be using a straw of semen known to have a high concentration of defects.
1. Sperm cell defects are common in all male species but should not exceed ______percent.
2. List five common defects found in sperm cells that we covered in class.
A.
B.
C.
D.
E.
3. Label the parts of a healthy sperm cell.
4. List the sperm cell defects you were able to find?
Sperm Cell Concentration Lab
Name ______Date ______
Background
The number of sperm cells or concentration is probably the most important variable relating to fertility soundness in the male. There are a number of ways to calculate sperm cell concentration. For this lab we will be using a hemacytometer. This is the same method used locally in our hospital labs when doing fertility testing on humans. A hemacytometer utilizes a special cover slip and a grid that can be used to calculate the number of sperm cells in a sample. One ejaculate from a bull will typically produce 4-6 milliliters of semen containing around 6-8 billion sperm cells. AI companies, after careful inspection, add semen extenders and other agents to prepare it to be frozen, and place the semen into ½ cc straws. One ejaculate will make approximately two hundred straws. As a result, we will not see anywhere near the number of sperm cells as would be seen had the semen been evaluated directly from the animal. The purpose of this lab is to familiarize you with the basic concept of how the procedure is done.
Instructions
The Ag instructor will walk you through the process of how to load the semen into the hemacytometer and get it set up on a microscope. On low power, find the center grid which will be a 5 by 5 grid with each cell containing a 4 by 4 grid as illustrated below. Then switch to the next higher optical lens on the microscope. You should be able to see the entire 5 by 5 grid in the field of view. Starting in the top left hand corner, count all the sperm cells you can see within the grid and record the number in the table below. Now move to the square to the right of it and count all the sperms cells in that square. Continue this until you have counted all twenty five squares and recorded the number of sperm cells in the corresponding box.
Use the following information, to provide the mathematical formula to calculate the total sperm cell count:
1. What was the total number of sperm cells found within the grid on the hemacytometer?
Number of sperm cells counted within the grid? ______
2. Calculate the concentration by taking the total sperm count on the grid times 10. This will give you the sperm count per cubic millimeter.
Sperm count per cubic millimeter? ______
3. Depending on the bull and the quality and volume of the ejaculate, the semen will be diluted down to a factor between 1 and 10. For the purposes of this lab we will use a dilution factor of 5. A dilution factor of 5 is a 1:5 dilution or 1/5 as concentrated. In this example multiply 1/5 or 0.2 times the sperm count per cubic millimeter found on question 2.
Number of sperm cells per cubic millimeter with the dilution factor? ______
4. 1 cubic centimeter contains 1000 cubic millimeters. (10 X10X10) The straws of semen are ½ cc or cubic centimeters or contain 500 cubic millimeters. To calculate the total number of sperm cells contained in a straw, times the sperm count per cubic millimeter times 500.
Total number of sperm cells in a straw? ______
5. Most ½ cc straws should contain around 50 million sperm cells. According to our calculations, are there approximately 50 million sperm cells?
6. What variables could lead to inaccurate results?