On Thursday, I was able to watch fertilization occur!
In lab, we used sea urchins (SU) to watch fertilization. I scooped out my own sea urchin from the tank and put it in the holding bin. While there, named the SU Terry (a unisex name). As Terry was getting acclimated to that water, I got a cup filled with sea water, a petri dish, a needle, potassium chloride, and paper towels. I also put on gloves. It was time.
I got Terry and placed it on the petridish. I turned it over to expose its bottom. Poor thing was not happy. The needle was filled with 1 milliliter of potassium chloride. Angling the needle between the needle portion and the opening, I injected Terry with 0.5 milliliters of potassium chloride. Poor thing was in pain and writhing around. :(
After about a minute, the gametes started flowing out of Terry. It was white, so we determined that Terry was in fact a boy! So we collected the rest of the sperm in the petri dish.
To watch fertilization, I got another group's eggs and put 1 drop of it on a microscope slide and covered it with a cover slip. Then, I got a small beaker and filled it with 10 ml of water. I then pipetted some of the sperm in the water to activate it. After focusing on the eggs under the microscope on the 40x objective, a drop of sperm solution was added to the slide. Looking at the slide, I was able to see the sperm vigorously swimming around. Looking at the eggs, it was clear to see which sperm fertilized eggs. It was also cool to see the fast block prevent polyspermy. The most awesome part was watching the fertilization envelope develop.
Just to watch what we have been learning occur before my very eyes was beautiful. It helps to make a lot of the concepts make sense.
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