After years and years of trying, the first puppies conceived via test-tube method have been born. How the attempt finally succeeded can be credited to a number of breakthrough techniques discovered by the scientists as they went through the process.
In vitro fertilization (IVF) is the method used to create the world's first test-tube puppies. Such technique is also widely used by humans to produce babies every year.
Producing dogs via assisted reproductive technologies (ART), however, has been elusive of success because of dogs' unusual reproductive system.
"Dog reproduction is very, very different from that of other mammals," said co-author Alexander Travis from Cornell University.
Ultimately, it took approximately 20 years for seven test-tube puppies to finally be born.
Some methods during the entire experiment had to be tweaked in one way or another for success to happen. After a considerable amount of time spent on the endeavor, the researchers were able to determine five important things that influenced the success of the study.
Magnesium magic
The chemistry of the female system has to be artificially imitated once conception begins in a dish. Such step has hindered past scientists from becoming successful. In a new attempt, however, scientists were finally able solve the puzzle by using a formula that is high in magnesium. Magnesium is said to have the ability to prepare the sperm efficiently in a matter of four hours only.
Timing is the key
Another vital factor that contributed to the success of the endeavor is determining the correct timing of obtaining the female dog's oocyte or egg cell.
As per analysis, the team was able to discover that the optimal time for getting a competent egg cell is six days after the surge of the luteinizing hormone, so that is what they followed.
The role of progesterone
Progesterone is recognized to play a part in the physiological release of acrosome, which is a granule critically important for fertilization to take place. Magnesium is said to enhance acrosome exocytosis and with its inclusion in the formula, the scientists concluded that progesterone has no significant effects on embryo generation.
Male donor importance
Sperm hyperactivation is a vital factor in the success of IVF birth in puppies. When magnesium was added to the equation, the sperm from the male donor exhibited hyperactivity and was given a remarkable ability to undergo natural acrosome exocytosis, which are two of the most critical factors for successful egg fertilization.
Ice, ice baby
The egg cells of dogs are dark in color because it is high in lipid content, making it hard for experts to cryopreserve viable eggs and embryos. In the new study, however, the researchers decided to push through with cryopreservation and transferred the embryos to the oviduct.
The result?
They were able to produce 19 embryos from different dog parent combinations and implanted them inside a female dog's uterus. The female dog used was not a genetic parent of any of the puppies.
A total of seven embryos, four males and three females, were successfully attached to the womb. All the seven embryos were able to reach term and when they came out via Cesarean section after 63 days, it looks as if there were no signs of their unique beginnings.
Aside from amping up the species' population, the idea of creating test-tube puppies is rooted from the desire to produce dogs that are genetically manipulated. Puppies that are free of disease-causing genes may perhaps save endangered species in the future.
The study was published in PLOS One journal on Wednesday, Dec. 9.
