PARENT SESSION
EDUCATIONAL EXHIBITS

Monday, August 2, 2004
10:30 AM–12:30 PM
Buchanan Courtyard

(58) LABORATORY EXERCISE: FUNCTION OF SPERM HYPERACTIVATION.

Suarez, Susan¹, Kaproth, Michael^{2, 3}, ¹ Cornell University, Ithaca, NY² Cornell University, Ithaca, NY³ Genex Cooperative Inc., Shawano, WI

ABSTRACT- This laboratory exercise enables students to learn about the role of hyperactivated sperm motility in fertilization. Hyperactivation is an increase in flagellar beat asymmetry and bend amplitude undergone by sperm nearing the site of fertilization. This exercise can be done by students in high school through graduate/professional school. For high school students, it is exciting just to see sperm swim; more advanced students are impressed by the dramatic change undergone by hyperactivated sperm. Students work in pairs. First, they thaw bull semen that had been frozen in egg yolk extender in a 0.5 ml commercial artificial insemination straw. The thawed semen is layered under 1 ml of warm TALP medium (39 C) and placed in an incubator for 30-60 min to allow motile sperm to swim up into the medium. During this time, a lecture can be given on sperm motility and transport through the female reproductive tract, as well as on sperm freezing and artificial insemination. Alternatively, the semen can be diluted directly into 1 ml warm TALP and used immediately. Students examine the sperm under the microscope and note how they swim in a linear path. Next, students take an aliquot of sperm and treat it 1:1 with 10 mM procaine in warm TALP for 60 sec to induce hyperactivation. When they examine these sperm, all are swimming vigorously in the circular pattern of hyperactivated motility. The students can then test whether these sperm are more effective at swimming in a viscoelastic environment, representing mucus in the oviduct and the cumulus matrix. Students inject an aliquot of hyperactivated sperm under a drop of 2% polyacrylamide solution in warm TALP, add a coverslip, and observe how the sperm swim. Then they compare movement of hyperactivated sperm with that of non-hyperactivated sperm in polyacrylamide on a duplicate slide. Hyperactivated sperm straighten out in this medium and penetrate it more quickly. The comparison can be done with the observer blinded to treatment, providing a lesson in reducing bias from experiments. This project was supported by the donation of frozen bull semen by Genex Cooperative, Inc., Shawano, WI.

KEY WORDS: laboratory exercise, oviduct, sperm motility, sperm transport