If 100 fertilised eggs were planted in 100 females uteri at the correct time in their menstrual cycle, only 18 of these eggs would be born. At a certain point during a female’s menstrual cycle, blisters form within the uterus and mucus is then secreted. The gene that produces this mucus is MUC1 – the mucin gene. This mucus and therefore this gene, is associated with breast cancer, which therefore means that a mutated mucin gene could contribute or be a cause of breast cancer.
A normal fertile female has 5.5 kilobases. Although rare, some females can have just 3.5 kilobases. This affects the lining of the uterus ultimately resulting in infertility as the uterus becomes inhospitable. Fertility declines with age, as the uterus becomes more inhospitable. Moreover, many more eggs/embryo’s have severely mutated chromosomes as either a result of a mutated mother egg/cell, or as a result of DNA copying errors as the cell/egg multiplies. This decline in fertility is so severe that by the time a female reaches the age of 45, there is only a 2% chance of her giving birth to a child after having IVF treatment.
However this is not so with the oldest living organism on the planet being 3000 years old – a tree, still producing saplings! How the number of eggs in a female declines throughout the years: At 16 weeks, the female foetus contains 7 millions eggs, however this number decreases as the cells die – apoptosis (cell death). By birth, nine weeks, a female baby has only 2 million eggs contained in her uterus. Despite these relatively large numbers, females only use 360 eggs in a lifetime, although as mentioned above, the eggs a female releases later in her life are much less fertile.
> One way of combating this infertility in older women is to insert mitochondria from a donor egg into a recipitant egg, which means the cell has/can produce much more energy to divide and therefore develop into a foetus. However, there seems to be a very serious implication of using this method to manipulate reproduction as well as the ethical issues involved, many of the children born using this technique have chromosome mutations, which are potentially lethal.
This manipulated/aided reproduction has the potential to produce a child with up to 5 parents: I. Donor sperm II. Donor egg III. Donor Cytoplasm IV. Donor mitochondria V. Surrogate Mother Using embryonic cells to test for genetic disease/mutations: It is possible to safely remove a single cell from an embryo without destroying the other cells that make up the embryo. In doing so this creates a number of possibilities for testing the embryo against genetic diseases and mutations.
Using this method it is possible to predict whether or not the embryo will survive long enough to come to full term and therefore be born. Moreover it is also possible to see if the embryo has inherited any genetic disorders or even developed any genetic mutations as a result of DNA copying errors. This can either prepare the parents or have more adverse effects for example termination of the pregnancy. For this reason Ethics must be involved when using this test.
Under the umbrella of cell mutation is the repeated copies of some chromosomes, for example three copies of chromosome 18, which is linked to miscarriage. This means that although embryos with mutated chromosomes are born, in lots of cases those embryos that have many mutated chromosomes, the embryo simply dies, there are too many mutations for the embryo to develop into a baby. Thus apoptosis occurs – cell death. The embryo dies and a miscarriage occurs. However if the environment intervenes and allows the abnormal cells to develop and be born, the chromosome mutations can be such that the baby is diseased or disfigured.
The female body produces FSH (follicle stimulating hormone) naturally, however research has found that when a pregnant female is injected with a large dose of FSH, the embryo changes, i.e. the chromosomes within the embryo become mutated. Quantification of TSC2 mRNA transcripts after embryo freezing: When a female develops cancer and chooses to undergo a course of chemotherapy, the radiation can permanently mutate her eggs, thus making her infertile or at least unable to give birth to a child that has not got a genetic mutation/disease.
To overcome this problem many females have, there have been suggestions to use a technique called ’embryo freezing’. At first glance this technique is wonderful in that it means cancer patients do not have to become infertile. However, close examination has proved that embryo-freezing leads to changes in gene expression, in other words the genes are mutated and may therefore cause a greater susceptibility to cancer.