Emma King answered on 17 Mar 2011:
Hi ninjasaurus. Good question! I think a lot of people get confused. We can take stem cells from a variety of locations including adults and umbilical cord blood, but I think what you are meaning is the distinction between an embryo and a fetus.
An embryo is the very early stages of cell division after a sperm and an egg have fused (fertilisation). In the normal human body this would then implant into the womb and might grow on to form a baby. If people have problems conceiving the fertilisation bit is done in the lab – and if there are too many embryos made or they are not very good quality then they can be donated for research (if the parent’s agree). These embryos can only be used up to 14 days after fertilisation.
In the UK we are also allowed to do research on fetal tissue, but it’s much rarer. A fetus is an embryo that is further down the pathway to growing into a baby (about 8+ weeks after fertilisation). This tissue can only come from people who have had abortions and choose to donate this tissue for research.
We also do research on eggs – these are donated by women but have not been fertilised.
I hope that helps!
Sharon Sneddon answered on 17 Mar 2011:
All human life starts with an egg (from the mum) and a sperm (from the dad). At fertilisation, the sperm nucleus enters the egg and everything fuses together. This makes a zygote and it still only has one cell, but it now has the right amount of chromoomes and all the genetic information required to make a human being. At this point, if everything is going to plan, the cell starts to divide into 2, then 4 then 8 then 16 cells, this takes about 2 days, on day 3-4 the cell number increases to 32 then 64 cells, at this point, the ball of cells, which is now called an embryo undergoes a process called compaction and this is the first time when the cells start to make a decision, some of the cells will decide to become placenta type cells, so they will not make up the cells of the embryo. The placental cells move to the outside and the embryo cells are in the middle of the ball of cells. It’s at this point we would take the embyo cells to make embryonic stem cells and this happens about 5 or 6 days after fertilisation.
If the embryo is still in the womb , it is at this stage that the embryo would implant (attach) to the mother and the placental cells will make the placenta, and the embryo cells keep on dividing until all the structures that form a human are made.
After about 9 weeks, the embryo will have all the major organs like the heart, the brain and the lungs have formed. It’s at this stage that it is called a foetus.
hope this helps!!
James Chan answered on 18 Mar 2011:
No worries, it’s ok cos I get confused a lot too by all these different terms!!
ok, so, once an egg is fertilised by the sperm, you get a zygote. The cell then starts dividing and becomes an embryo, and that continues so that some cells start forming different organs, and you get a mini-me, or a foetus.
So most of the cells become specialised, like nerves, or liver cells, or skin cells. A small number of cells do not become specialised but they have the POTENTIAL to become specialised if given the right signals – these are what we call stem cells.
So, we think stem cells are exciting because if we know what signals to give them, then we can ask them to turn into any of the different types of cells. For example, in my research, I look at speeding up the healing of broken bones. so I can give the stem cells a signal to turn into new bone!
Many people get confused because people talk about different types of stem cells. The main 2 types are embryonic (which are from the embryo) and adult (from anybody who’s been born, essentially). The only difference is that the 1st type from the embryo are able to turn into more different types of cells whereas the adult ones are a bit more limited, for example, the ones I use can turn into fat, bone or cartilage but cannot, for instance, become a liver cell.
I hope that’s cleared things up a little. Do you understand now?
in our lesson we had a debate about wether people should use stem cells from embryo's or adults, what do you think?!
do you need volunteers for stem cell research?
Do you believe that we should use stem cells from aborted foetus?
How do you react to people, that think stem cell research is unethical?
As, a stem cell scientist, when do you believe life to begin = the embryo or the actual baby formed?