The world is full of birds chirping, fluttering, and waddling. It has feathers, a beak, and claws. These incredibly diverse animals are the closest living descendants of the majestic dinosaurs and have successfully made their home across the globe.
However, some parts of the breeding process are still somewhat mysterious. The time a growing chick spends hidden inside an opaque eggshell, the time it hatches from a zygote, completes its development, and grows into an adult is under the loving care of its parents.
Now a long-standing goal in avian developmental biology has been realized. A team of scientists has developed a system to culture eggs that replace the opaque eggshells of domestic white leghorn chickens.Gallus Homestequus), you can almost observe the embryonic development of the bird.
The team’s shellless culture system was so successful that several of the chicks successfully hatched at the end of their normal incubation period and grew into normal chickens.
Scientists have been working for decades to develop shellless culture systems (SLCS) to observe the development of embryonic algae. Previous methods that showed promise; First described in 2014It involves allowing the embryo to develop within the egg for three days. What an embryo needs to surviveIt is then removed into a culture vessel protected with a sheet of polymethylpentene kitchen adhesive film.
However, this system was not perfect. The hatching success rate was greatly reduced as the chicks failed to grow normally.
The method’s pioneer, veterinary scientist Katsuya Obara of Okayama University of Science and Technology, led a team with colleague Chizuka Obara to solve one of the problems that hinder normal development and hatching.
yolk vitelline membrane It serves to protect the cell layer around the embryo. blastoderm The team thought this could interfere with normal embryonic development.
Therefore, to prevent the membrane from drying out, the team mounted the culture vessel on a rotary shaker, which is typically used to create continuous motion for mixing. The angle of the top plate of the shaker was set at 7 degrees, and the experiment was conducted at different cycles of 6 rotations per minute, 10 rotations per minute, and 28 rotations per minute.
This prevented the membrane from drying out due to the continuous flow of albumin, but the development and survival period varied up to 10 days.
Survival was highest at 6 revolutions per minute, but all embryos showed signs of developmental delay.
At 10 revolutions per minute, survival was slightly lower and some embryos developed abnormalities, but survival of normal embryos was strong.
And at a speed of 28 rotations per minute, all embryos showed abnormalities that made them non-viable after 10 days.
With 10 revolutions per minute being the optimal speed for both survival and development, the researchers experimented with adding oxygen to the developing embryos at various time points past 10 days. Oxygen must be added, but when this occurs does not really affect embryo development.
Finally, they performed the same experiment, adding supplemental oxygen and sprinkling calcium carbonate powder (the stuff eggshells are made of) at 10 revolutions per minute, but this time implementing additional shaking of the culture vessel by hand. . This was performed 3 to 5 times every 3 to 10 hours during the first 24 to 48 hours of shell-free culture.
This method resulted in the highest hatching rate of normal chicks. At 10 revolutions per minute with oxygen, the hatch rate was 3.3%. Adding a hand rocking motion back and forth increased the speed to 10.5%.
One of the hatched chickens was grown for 1 year and then euthanized and dissected. It was completely normal. The system is successful. It provides a literal window into the development of chickens until they hatch.
“The development of visible-cSLCS opens new possibilities by facilitating omnidirectional, real-time monitoring of the phenotypic outcome of experimental treatments through transparent plastic films from blastoderm stage embryos until hatching.” Researchers write on papers.
“This system will serve as a powerful tool in a variety of fields, including toxicology, stem cell research, bioimaging, and regenerative medicine.”
The team’s findings were published as follows: scientific report.
