In what could be a major breakthrough for fertility treatment, unlimited egg supply for women may be a step closer following new stem cell research.
The study, published in the journal Nature Medicine, challenges the long-held belief that women are born with a finite supply of eggs that will be exhausted by menopause.
Scientists isolated stem cells in the ovaries of reproductive age women and found they can produce immature eggs (oocytes) in laboratory conditions – and further tests on mice revealed the eggs could be fertilised.
The study is not the first to dispute the notion that a woman’s egg supply is gradually depleted, running out by middle age.
Lead researcher Dr Jonathan Tilly, from Massachusetts General Hospital, first questioned this theory in 2004 in a study that revealed mice have some egg-producing stem cells.
Dr Tilly said: "The primary objective of the current study was to prove that oocyte-producing stem cells do in fact exist in the ovaries of women during reproductive life, which we feel this study demonstrates very clearly."
Researchers found the stem cells, which go on to produce oocytes, by searching for a protein that is unique to the surface of the stem cells.
Oocytes are immature female sex cells that mature to give rise to a fully mature egg cell.
The researchers grafted human ovarian tissue around the stem cells inside mice and found they “spontaneously generated” egg cells that looked and acted like oocytes.
Tilly added: "The discovery of oocyte precursor cells in adult human ovaries, coupled with the fact that these cells share the same characteristic features of their mouse counterparts that produce fully functional eggs, opens the door for development of unprecedented technologies to overcome infertility in women and perhaps even delay the timing of ovarian failure."
Rachel Cutting, Chairman of the Association of Clinical Embryologists, told The Huffington Post:
"The study is very exciting as it shows that eggs can be made from stem cells in the ovary which completely changes our understanding that women are born with a finite number of eggs.
“The study not only shows that cells form with oocyte properties but in mice these cells could be fertilised as well. If developed further, the technique could go a long way to help infertile women overcome problems such as early menopause and preserving fertility before cancer treatment.
“Whilst ACE supports all research which helps overcome infertility, further studies are needed to look at how the fertilised eggs from the research develop as embryos and to check the safety of the technology."
Dr Allan Pacey, a fertility expert at the University of Sheffield, told the BBC: "This is a nice study which shows quite convincingly that women's ovaries contain stem cells that can divide and make eggs.
"Not only does this re-write the rule book, it opens up a number of exciting possibilities for preserving the fertility of women undergoing treatment for cancer, or just maybe for women who are suffering infertility by extracting these cells and making her new eggs in the lab."
Although there is no direct link between refined carbohydrates and infertility, the refining process strips grains of some of the most important fertility-boosting nutrients, such as antioxidants, B vitamins and iron.
Modern methods of food production, involving intensive farming, rob the soil of vital nutrients, so where possible stick to organic produce. Processed foods are packed with additives and preservatives that can upset blood sugar levels and disrupt the body's hormonal balance.
Too much red meat increases the amount of ammonia in the body, which can interfere with the implantation of the egg in the uterus. Red meat can also be detrimental for men as it increases acidity and affects sperm activity; sperm perform better in alkaline conditions.
The animal hormones in dairy products can affect your own hormonal balance. If you balk at the richness of soya milk and can't bear to give up your semi-skimmed, switch to organic dairy products instead as these contain lower levels of hormones.
Giving up alcohol is not strictly necessary until you fall pregnant but it might be worth bearing in mind that Danish research, studying the link between alcohol consumption and fertility, found that alcohol intake had a significant effect on infertility success among women above the age of 30 who drank seven or more drinks a week.
While you don't need to give up your morning coffee, caffeine does constrict the blood vessels, slowing blood flow to the uterus and potentially making it harder for an egg to grab hold. So, if you're having any trouble conceiving, or undergoing IVF treatment, you might want to go easy on the double espressos.
Aside from being packed with vitamins and minerals, fruit and vegetables are packed with antioxidants that attack free-radicals (harmful molecules that can damage the ova, sperm and reproductive organs).
Zinc helps to maintain a healthy menstrual cycle as well as being vital during pregnancy to aid cell division in a developing foetus. Folic acid (Vitamin B6), together with zinc, is essential in the function of female sex hormones. Vitamin B12 is also very important as it maximises the absorption of folic acid. Taking a multi-vitamin tablet designed especially for conception is a good way to ensure you're getting enough of these valuable nutrients. Marmite is also a great source!