The first puppies conceived through in vitro fertilization (IVF) were born not too long ago, helping scientists better understand the process of reproduction in domestic dog, according to a new research.
Seven healthy puppies were born by scheduled caesarean section to a female dog. Two of the puppies have a beagle mother and a cocker spaniel father, and five of them have beagle parents.
In vitro fertilization (IVF) is a process in which the egg is fertilised by sperm in an artificial environment outside the body: in vitro (“in glass”). The fertilised egg (zygote) is cultured for two to six days, after which it is implanted in a host that carries it to full term (with the intention of establishing a successful pregnancy).
In the 1950s, the first IVF rabbits were born, and the first human, Louise Brown, was born through in vitro fertilisation in 1978. According to a paper published in the Journal of In Vitro Fertilization and Embryo Transfer, IVF produced tens of thousands of pregnancies and offspring in domestic cattle by the 1980s.
However, Alex Travis, co-author of the study and an associate professor at the Baker Institute for Animal Health at Cornell University College of Veterinary Medicine, said that dog reproduction is different from other mammals, which made it more difficult for IVF to work on dogs.
The animals come into heat about two times per year, which creates scheduling difficulties for researchers. But most importantly, when a female dog ovulates, the egg is not ready to be fertilised straightaway, according to Travis.
While in most mammals when an egg enters the fallopian tube it is ready for fertilising, female dogs produce immature eggs that have to remain in the oviducts for one to two days to mature, before they are viable.
Travis said that even when they let the egg mature, the IVF turned out to be unsuccessful, so they had to also take a look at the sperm in their fertilisation equation.
The researchers found that magnesium was a missing ingredient. Even though a previous study suggested that magnesium prevented sperm’s heads and tails from developing properly, researchers at Cornell University found that magnesium actually stimulated the sperm, Travis explained.
Once they added magnesium, the fertilisation rate increased by 80 to 90 percent, according to Travis. The final step was to freeze the embryos before they could be implanted in the host dog.
The findings were published December 9 in the journal PLOS ONE.
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