6 minutes

“Its hard to wait around for something you know might never happen but its even harder to give up when you know its everything you want.” – Author unknown1 

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Bond between Mother & Child (Creative Common Photograph taken from Wikipedia)

              Life is a continuum, from the time the egg is fertilized, to the time we are born, from childhood to adulthood, and then finally to old age. Nonetheless, this amazing process of human development begins at fertilization. Fertilization is the story of how a single sperm facing incredible odds unites with an egg to form a human life, this is the story of all of us, well actually most of us.

              During sexual intercourse, around 300 million sperm make their way into the vagina2. However, millions are unable to survive due to the acidic environment. Subsequently, the sperm pass into the cervix and swim through the cervical mucous into the uterus. At times, some sperm take a break coating the uterine walls, and may or may not join the race towards the egg. Muscular uterine contractions assist the sperm to get closer towards their goal. However, the women’s immune system mistakes the sperm for pathogen invaders, resulting in the destruction of thousands of more sperm2. Subsequently, the sperm divide in half, either going into the empty fallopian tube, or the one containing the unfertilized egg2. Now, there are only a few thousand remaining. The cilia inside of the fallopian tube guide the egg towards the uterus, and in order for the sperm to continue swimming, it must surge against this force2. In the duration of this part of their journey, chemicals produced in the reproductive tract result in the sperm head coverings to change, making them become hyperactive and swim harder and faster to their destination2. Finally, the moment everyone has been waiting for, the sperms (only about a dozen) reach the egg. The sperm must push through the corona radiata, which are the layer of cells covering the egg, in order to reach the zona pellucida (egg coat) 2. When they reach this layer, they attach to specialize sperm receptors on the surface which triggers their acrosomes to release digestive enzymes, enabling the sperm to burrow into the layer. This process is called the acrosomal reaction. Inside the zone pellucida, there is a narrow fluid filled space just outside the egg cell membrane2. The first sperm to make contact wins the race! After an incredible journey a single sperm attaches to the egg cell membrane. The outer membrane fuses and the egg pulls the sperm inside. The two sets of chromosomes, 23 paternal chromosomes and 23 maternal chromosomes, fuse together to complete the process of fertilization.

An animation of the stages of development during pregnancy by Ashish Khera. (CC by 3.0)

               Although most people reproduce through traditional vaginal intercourse, there are some that may encounter difficulty in doing so. According to the World Health Organization, an estimated 34 million women, predominantly from developing countries are unable to have children with their spouse3. This cause may be due to fertility problems in both women and men. Women with ovulation disorders, polycystic ovarian disease, damaged fallopian tubes, endometriosis and men with sperm abnormalities, such as varicocele, may never be able to conceive through intercourse4. However, in some instances a cause for infertility is never found. It is possible, that a mixture of many factors in both partners can influence these undetermined fertility problems.

“I found that each time a test was negative, it stopped the dreaming and hoping for a while. Taking the test was a way of puncturing the balloons of hope, because if I didn’t, they would lift and lift without any evidence, and their falling back down every month was too painful. Essentially, I took all these tests to keep myself from hoping, because the hoping was breaking my heart.” ― Shauna Niequist5

……This was BEFORE a cure was found!!!

            Now, there IS a major treatment for infertility, and this is known as in vitro fertilization. This process consists of three major steps follicle aspiration, fertilization, and embryo transfer. Before in vitro fertilization, a woman receives fertility medication that causes more than one egg to grow and mature in the ovaries6. Next, sperm is collected from a donor6. During the first procedure, eggs are harvested from the ovaries6. An ultrasound probe is inserted in the women’s vagina to view the ovaries6. Inside the ovaries, the doctor looks for follicles which consists the eggs6. The doctor then inserts a needle into and through her vagina, and the suction device at the end of the needle sucks the eggs6. The collected eggs will be fertilized and the embryos will be monitored for 3-5 days as they begin to grow6. Finally, the embryos will be transferred back into the woman’s body through a needle.

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Process of in vitro fertilization. (Creative Commons Photograph taken from Wikipedia)

              Of course, this process is beneficial as it finally lets people who cannot conceive, turn their dreams into reality, so what can be possibly wrong with that, right?…

              …Unfortunately, choosing this route has its disadvantages as it can increase the chance of having twins, triplets, or even more children than expected7. In addition, this procedure is very expensive as it can cost around $7,750 – $12,2507. Although this seems like a promising solution, the success rate of cycles that result in live birth is known to be just above 25%8. Moreover, it has been discovered that IVF babies are found to be at more risk for genetic defects in the long run, than naturally conceived babies9. Finally, there is the intricate question of the possible ethical impacts on society and culture. There are many people that are against this process as they consider this as an unnatural act10. Some believe there is a reason people are infertile, as it is a part of your fate10. Additionally, some people argue that you’re essentially putting the unborn child’s life in danger due to the potential side affects that could arise10. Beyond this, there are several cases in which IVF provides more benefits to the unborn child as opposed to risks. Perhaps the most significant is when a mother with a mitochondrial disorder wants to have children. Through fertilization, whether IVF or traditional means, all of her children will inherit the disorder as the mitochondria are inherited strictly maternally11. These chronic diseases result in a genetic disorder that give arise to organ malfunction due to the mitochondria of the cell failing to produce sufficient amounts of energy11.

BUT…… on a count of three, 1, 2, 3….

               With recent technology scientists have now come up with a new method which can resolve this matter. This process will permit mothers who carry a specific genetic condition to conceive children with their genetic code, however without the mitochondrial DNA (mtDNA), that can result in chronic diseases/illnesses12. This process, “The three parent technique”, involves in vitro fertilization consisting of the mother’s eggs, the father’s sperm, and the use of a donor’s undamaged mtDNA, allowing the creation of a child with three biological parents12. The mitochondrial transfer can be accomplished by two different methods. The first method consists of the nucleus (parent’s genetic material) being removed from an egg that has faulty mitochondria13. The nucleus is then injected into a donor egg that is stripped of its genetic material, however is left with contains healthy mitochondria13. The embryo is then fertilized, and returned back into the mother’s uterus13. The second method involves fertilization of the two eggs, and moving them into the pronuclei from the mother’s embryo into that of the donor, and then transferred back into the mother13. The resulting child will have 30,000 genes from the parents (egg/sperm) and 0.1% genetic code will be from the mitochondrial donor, thus a child with three biological parents14.

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The two methods of mitochondrial transfer during IVF. (Permission from NINDS)

               If this route is taken, scientists say conditions such as blindness, certain heart diseases, and muscular dystrophy do not get passed on to the next generation15. It wasn’t until recently (2015), that the British government approved this process to spare any future sufferings, however Canada seems to be reluctant13. In 2004, Canada passed the law that states no person can knowingly “alter the genome of a cell of a human being or in vitro embryo such that the alteration is capable of being transmitted to descendants16.” However, according to the MitoCanada (supporters of this process), 1 in 5 000 people in Canada suffer from this mitochondrial disease16. Hopefully within the near future this law can be revisited. Unfortunately, treatment for this disease is limited and there seems to be no existing cure16. Moreover, many children with this disease don’t live past their mid-teens16. Therefore, given the lack of treatments and the limitations of the mitochondrial disease, this is a viable approach for women with mitochondrial diseases.

Video accessed from: https://www.youtube.com/watch?v=rCKeRUMO0DY

             In conclusion, I find IVF to be a great solution to people who are unable to conceive children. Moreover, future advancements brought about by the emerging three parent technique using a mitochondrial donor will be a useful tool for studying evolution, since mtDNa alters more rapidly, than other parts of the genome13. Due to this, mtDNA can cause other diseases involving the heart, brain and respiratory system13. To conclude, by implementing and further researching this method of fertilization, we can further our ability to cure genetic diseases while giving people who in the past had limited chances of having healthy children the ability to conceive a child. To me this is the best of both worlds since everyone deserves the choice of having a family!

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The Griffin Family from Family Guy. (Creative Commons Photograph taken from Wikipedia)