動物園表親的野生犀牛體外受精幫助

Zanta, a 22-year-old rhino at Dublin Zoo, has had her eggs collected. Collecting eggs from a two-tonne rhino is far from easy, but the procedure is being carried out in zoos across Europe to help the wild population. The hope is that cutting-edge fertility technology could boost the genetic diversity of southern white rhinos in Africa. The species was almost extinct, plummeting to a few dozen rhinos, so the animals are all descended from this tiny group. Scientists believe rhinos in zoos, which have more genetic diversity because they are carefully crossbred, could widen the gene pool with the help of IVF.

Zanta was selected for the procedure because she can't have calves of her own. One of the animals taking part in the southern white zoo project is 22-year-old Zanta from Ireland. 'Zanta has wonderful genetics that are worth preserving, but we know from a previous reproductive assessment that she can’t breed,' says Frank O’Sullivan, a vet at the zoo. 'The main reason we want to do the procedure is to bypass that, harvest her eggs and then they'll be fertilised. The great thing is Zanta will be represented in future generations of rhinos.

It has taken many years to work out how to extract eggs from a rhino. A team of fertility specialists from Germany has flown to Ireland to carry out the procedure. Zanta is anaesthetized with a dart, then once she’s fully sedated the scientists get to work. Amidst the regular beeps of the equipment monitoring Zanta’s vital signs, the researchers cluster around a screen that’s showing an ultrasound of the rhino’s ovaries. She’s been given special hormone injections to help her produce eggs. The researchers are able to locate them inside follicles, small sacs of fluid, that appear as black circles on the screen. Using an ultra-fine needle, and a great deal of precision, they are able to extract the eggs.

The IVF pregnancy announced in January was in southern whites, with the team successfully transferring a lab-created rhino embryo into a surrogate mother. A calf was never born because the mother died from an unrelated bacterial infection early in the pregnancy. However, the scientists believe the pregnancy shows the technique is viable. Their ultimate aim is to repeat this with the southern white rhino’s all but extinct cousin, the northern white rhino, for a project called Biorescue. There are only two of these animals left on the planet, both of them females. But the scientists believe the reproductive advances they’ve made could also help with the southern white rhino’s genetic problems.