Sperm Science

Zoo InternQuest is a seven-week career exploration program for San Diego County high school juniors and seniors. Students have the unique opportunity to meet professionals working for the San Diego Zoo, Safari Park, and Institute for Conservation Research, learn about their jobs and then blog about their experience online. Follow their adventures here on the Zoo’s website!

This week we met Carly Young, a Senior Research Technician in the Reproductive Physiology Division at the San Diego Zoo Institute for Conservation Research. Ms. Young walked us through her job and allowed us to do some hands on work with sperm samples from domestic cats.

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Sperm samples are collected via electro ejaculation, post mortem collection, or manual stimulation. All collected samples are then kept frozen in liquid nitrogen, waiting to be thawed before any research can be performed.

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Since sperm is found inside the body, Ms. Young and her colleagues use a body temperature water bath to thaw samples. After one minute of soaking the sperm we were ready to observe our sample of “cat junk.”

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These microscopes are a bit more complex than the ones we’re used to seeing in our high school classes, but they work great for zooming in on tiny sperm cells. As Intern Abby observed the cells, she counted how many were motile (meaning ability to move spontaneously and actively) and how many were stationary.

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Intern Marcel took advantage of the technology used in the Reproductive Physiology Division and projected the image of his slide onto a screen. Enlarging the size of the sample made it easier to count the active sperm cells and note how fast they were going. The speed of progression (SOP) of the sperm indicates how well the sperm will be able to fertilize an egg, a very useful tool when determining the potential of a sample.

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Besides observing the motility of the sperm cells, technicians in the Reproductive Physiology Division also determine how many of the cells are alive and dead. The sample is stained with eosin/nigrosin, which turns the heads of live cells white and dead cells pink.

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By using a pipette, we were able to add caffeine to the sperm sample to increase its speed of progression. After adding the caffeine, we observed a dramatic increase in the amount of motile cells and the overall speed of progression. Who knew caffeine could wake up sperm?

After concentrating the sperm into a pellet, re-suspending it in a M199 medium, and adding water, the Technicians observe the amount of coiled and non-coiled tails. This helps them determine the optimal environment for the sperm’s structure. Straight tails are better than coiled tails because they allow for faster motility.

After concentrating the sperm into a pellet, re-suspending it in a M199 medium, and adding water, the Technicians observe the amount of coiled and non-coiled tails. This helps them determine the optimal environment for the sperm’s structure. Straight tails are better than coiled tails because they allow for faster motility.

Jade, Photo Journalist Team
Week Two, Winter Session 2013

 

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