Researchers remove African lion in-vitro embryos after inactivation of neural oocytes

A team of scientists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) in Germany, Givskud Zoo – Zootopia in Denmark and the University of Milan in Italy successfully unveiled the first lion in-vitro embryos African after ingestion of neural oocytes. For this particular method of cryopreservation, oocytes are collected immediately after castration or death of an animal and immediately frozen at 19196 ° C in liquid nitrogen.

This method allows oocytes of valuable animals to be stored indefinitely, so that they can be used to produce offspring with the help of assisted reproductive methods. The aim is to further develop these methods and use them to eradicate endangered species such as the Asiatic lion. The current research on African lions as a model species is an important step in this direction. The findings are reported in the scientific journal »Cryobiology“.

Lion oocytes are thought to be very sensitive to cooling due to their high lipid content, leading to poor recovery after slow cooling. Vitrification can get around this problem, as the cells are frozen at ultra-fast speeds in solutions with very high densities of cryoprotective agents. This method prevents the formation of ice crystals in the cells, which could destroy them, and allows them to remain intact for an indefinite period of time until their later use.

For the current research, the scientists collected oocytes from four African lions from Givskud Zoo – Zootopia after the animals were hatched for the purpose of population control. Half of the oocytes (60) were immediately dissolved. After six days of storage in liquid nitrogen, the locked oocytes were thawed and subjected to vitromaturation in a refrigerator at 39 ° C for a total of 32–34 hours. The other half (59) were used as a control group and were introduced directly by vitromaturation without a degree of vigor. Mature oocytes of both groups were then fertilized with a frozen melt smear from African lion males.

We were able to show a high proportion of surviving and mature oocytes in the group of active oocytes. Almost 50% of them had matured, a similar proportion to the control group. “

Jennifer Zahmel, Scientist, Department of Reproductive Biology, Leibniz Institute for Zoo and Wildlife Research

Of the active group, seven embryos developed early, whereas in the control group only three embryos developed. “To our knowledge, this is the first time that inin-vitroembryos have been extracted after inoculation of oocytes from African lions or any other wildcat species,” said Martina Colombo of the University of Milan and a scientist hosted by the Leibniz-IZW.

In a recent scientific study of the domestic cat, conducted in collaboration with colleagues from the University of Milan and the Vienna Medical University, the Leibniz-IZW reproductive biology team showed that immediate vitrification of felid oocytes are the best choice to obtain a high number of good quality ovaries and as a result a higher number of developing embryos.

This study was also published in Cryobiology. On-site smelting is particularly useful if samples collected from wildlife are kept in a zoo and then transported to a suitable laboratory. “The transport of new oocytes and ovarian tissue across international borders is often complex and time-consuming, but the vigor of on-site oocytes allows a safe time for transport. The oocytes can be fertilized at a later stage. , once they have been transported to an appropriate laboratory and male sperm are available, “Zahmel explains.

Current research demonstrates successful vitrification, in-vitromaturation and fertilization of African lion oocytes for genetic resource banking. However, none of the progenitors developed from active oocytes beyond the 4-cell stage.

It would be important to clarify the pathways affected by adhesions to better understand the specific potential needs of trapped oocytes after thawing. “Although embryo development was still inhibited, our results suggest that felid oocytes may be cryopreserved and stored in biobanks in the future,” said Katarina Jewgenow, Head of the Department of Biology Reproduction at the Leibniz-IZW. “Our goal is to further develop these methods in model species such as domestic cats and African lions to be used one day for the assisted reproduction of endangered felids such as the Asiatic lion,” Jewgenow add.