Megan and Morag facts for kids

Megan and Morag were two domestic sheep that made history! They were the very first mammals successfully cloned from cells that had already started to specialize, meaning they weren't "blank slate" cells anymore. It's important not to mix them up with Dolly the sheep, who was the first animal cloned from an adult cell, or Polly the sheep, who was the first cloned animal that also had new genes added. Just like Dolly and Polly, Megan and Morag were cloned at the famous Roslin Institute in Edinburgh, Scotland, back in 1995.

How They Were Cloned

The Challenge of Genetic Modification

Scientists at the Roslin Institute wanted to find a better way to change the genes of sheep and cattle. Before Megan and Morag, the main method was called "microinjection." This involved injecting new DNA into the very early cells of a fertilized egg.

However, microinjection wasn't very efficient.

• Only a small number of animals would actually use the new DNA in their bodies.
• Even when the new DNA was used, it didn't always work in the way scientists hoped because it landed in a random spot in the animal's genetic code.

A New Approach: Nuclear Transfer

The team decided to try a different method. They combined ideas from microinjection with the use of embryonic stem cells. Their goal was to move the nucleus (which holds almost all of a cell's DNA) from one cell into another cell that had its nucleus removed. Then, they would try to make this new cell grow into a complete animal. This process is called nuclear transfer.

The scientists first tried to grow special "blank slate" cells from sheep that could keep dividing forever. But this didn't work out. So, they decided to use cells taken from a very early stage of development called a blastocyst.

The Cloning Process

Here's how they performed the nuclear transfer:

• They took the nucleus from a cultured blastocyst cell.
• They placed this nucleus into an unfertilized sheep egg cell that had its own nucleus removed.
• To help the process, they made the cultured cells "rest" so they were in a similar state to the unfertilized egg.
• They used small electric shocks to help the cells join together and to start the new cell developing into an embryo.

Out of 244 attempts at nuclear transfer, 34 embryos grew enough to be placed inside surrogate (mother) sheep. In the summer of 1995, five lambs were born. Two of them, named Megan and Morag (originally 5LL2 and 5LL5), survived and grew into healthy adult sheep that could have their own babies.

Megan and Morag were the very first mammals successfully cloned from cells that had already started to specialize. Their birth, a year before Dolly the sheep, was a huge step forward in cloning technology. It showed that it was possible to create living sheep from cells grown in a lab. In 2005, Megan was still alive, making her the oldest cloned animal at that time.

See also

• List of cloned animals