Tuesday, March 20, 2007

Tiger Project in Full Gear

Today marked a major uptick in our currently running Tiger Project. I'll elaborate a little on what, exactly, is going on. As I mentioned before, the HDZ is one of the leading instituions in research on tiger reproduction. The Tiger Project is part of that research. Last week we immobilized several female tigers and placed hormone implants under their skin. These implants release a hormone known as FSH (Follicle Stimulating Hormone) at a steady rate over a period of several days. As the name implies, this stimulates development of follicles on the ovaries of these cats and will (hopefully) bring them into heat and cycling in a manner so that we can appropriately time other treatments. In this instance, all of the tigresses responded to the FSH, showing strong signs of coming into heat as was expected and hoped for. This week (7 days after the implants were placed), the tigresses are being darted with additional hormones: GNRH (gonadotropin releasing hormone) and hCG (human chorionic gonadotropin) which will stimulate final development, materation and (untimately) ovulation. However, for the Tiger Project, we want to anesthetized these tigresses before they ovulate.

The goal of the Tiger Project is to collect the eggs so that other reproductive technologies can be used. The simplified version is that we collected eggs from this tiger (got 11 overall), several of which were then injected into her own Fallopian tube along with sperm that we collected from another Siberian tiger this morning in the hopes of getting some cubs! Also, some of these eggs will be transferred into other tigers so that those techniques can be standardized, also to get cubs.

"Big deal," you say. "Why don't you just let them breed naturally or just artificially inseminate them?" Well, there are a few reasons why. First of all, the goal of this research is to improve reproductive techniques in tigers so that natural breeding is not needed to ensure cubs. In order to maintain a healthy population of any species, it is important to maintain a diverse gene pool. For natural breeding, that would mean the nessescity of transporting male and female tigers all over the place so that they could be bred to unique individuals. By perfecting these techniques, we will be able to avoid that very time-consumming (minimal quarentine protocols and time to introduce animals takes literally months) and costly propositition. And as far as artificial insemination goes, it is historically extremely difficult in feline species, especially tigers. These other techniques are actually much more effective at producing cubs.

So, how is it done? With laproscopic surgery! Pictured at right is a laproscopic view of a tiger ovary with severeal very nice follicles. They appear as "blister-like" vesicles on the surface of the ovary. A needle is inserted into the follicles and the contents are litereally sucked out and collected. Then our reproductiove technologists exam the contents for eggs and grade their developement. Since we were putting several back into the tigress today, the opening of her Fallopian tube was then located and sperm and several mature eggs were put back in. This procedure is called gamete intrafallopian transfer or GIFT. Another method that we will be doing later this week you may have seen video of: where sperm is injected directly into the egg. This method is called intracytoplasmic sperm injection or ICSI. In-vitro fertilization (IVF or "test tube fertilization") has been done several times successfully here at the HDZ, but GIFT and ICSI show promise of higher success rates.

So, as you can see, it will be quite a full week! And hopefully it will result in many cubs! I'll end with a picture of Garth, the sperm donor of today. This is after he woke up from anesthesia and, as you can see, he isn't very pleased!

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