sperm-cells

Having shared and immersed, gluten-intolerance style, about political developments in Manipur with a bunch of strangers with their Pride and Prejudice  and with intimate conflicts about class and tribalism, like Jane-Austen-go-to Imphal, I am back to my favourite subject of science with the greatest hidden secrets, parking silently in the most unlikely places, like people in a bus at an abandoned location, sitting quietly as though they’re waiting for the bus to start again.

Modern research is turning human reproduction on its head. A group of researchers have fumbled an ancient idea screeching to a revolutionary up to date. The mystery of life for 200 years is now close to cracking an uncertain algorithm. In the middle of this September 2016, scientists at Bath University in England, are rewriting Nature by creating babies in mice without the participation of a female except for nurturing the embryo (unborn offspring) in her womb and giving birth to it. The babies will carry the same number of chromosomes as if it was born after fertilisation of its mother’s egg with its father’s sperm.

Dr Tony Perry, a molecular embryologist and author of the study said: “Our work challenges that dogma, held since early embryologists first observed mammalian eggs around 1827 and observed fertilisation 50 years later, that only an egg (ovule) fertilised with a sperm cell can result in a live mammalian birth. He claims that in the near future, human babies could be born without an egg.

I have an uneasy feeling that though God is not in scientific lexicon, even if he/she exists somewhere, must find it on the right side of becoming tiresome. This weird human reproduction would also be a dilemma for modern motherhood with her child wanting to know where the other half comes from unless it is her own skin cell, similar to IVF with a donor sperm from a bank. Feminist scientists are getting their knickers in a twist though the understanding is, it still needs a woman for the birth to go through.

A feminist, Emily Martin, an anthropologist and professor of socio-cultural anthropology at New York University, usually analyses science from a feminist perspective. She has poetry in motion about normal reproduction and Alpha male. The egg (the woman) in her view, reinforces our culture’s view of passive ‘damsel in distress’ image, while the active sperm (the man)like a knight in Arm, races to the egg to penetrate her. The truth is she says, the egg is not easy to penetrate as commonly believed. As a matter of fact, one sperm is not powerful enough to penetrate an egg and the egg’s barrier can only be weakened by the collective efforts of a number of sperms.

She adds, research at Johns Hopkins University, Baltimore, has shown that the sperm does not have a powerful thrust, and fertilsation occurs because the egg chooses who she lets in or not.  Once she has chosen a handsome sperm she closes the door by hardening its outer layer. Women feminist embryologists are now claiming that women produce eggs all their life as men produce sperms. As proof, scientists have discovered a new type of stem-cell in the human ovary that may point to the possibility of new eggs continually being formed throughout a woman’s reproductive years, like men who are constantly making new sperms (about 1,500 every second).

It’s a study provocative enough that scientists can manufacture humans on a conveyer belt with any cell in the body (that divides by mitosis, see below) fertilised by a sperm. To prove their point, three generations of mice have already been created using the technique. The mice are now well and healthy. Researchers are now planning to test the theory using human skin cells. This breakthrough is good news for gay couples and brings hope for women eg with cancer, who cannot conceive because of certain drugs or radiotherapy, to have their own children.

Scientists began experiments by making an egg believe that it is developing into an embryo by using chemicals as if it has been fertilised by a sperm. The cells in this false embryo copy themselves by dividing like the skin cells in the body, and controlling their DNA. Researchers have created a false mouse embryo into which they have injected a mouse sperm. The result has been the successful birth of healthy litter. They now believe that one day it will be possible to achieve a similar result in humans, using cells that are not from eggs.

In nature, a sperm out of millions that are courting an egg, if lucky enough to be received by a very choosy egg, will fuse with it romantically. Artificially, when a sperm is injected using IVF technique into the skin cell from which half of its chromosomes are removed first, an embryo develops. It is then taken into a surrogate woman’s womb to grow and be born.

Scientific account of normal conception between man and woman is now known more in detail than I learnt during my undergraduate medical training. An egg is about 4 times bigger than a skin cell and 16 times bigger than a sperm. Most eggs are present within the ovary in an immature state from the time of a woman’s menarche (first menstruation). For eggs to go through to their maturity and complete the journey to ovulation (discharge from ovary), they receive signals from brain, via two hormones. First, Follicular stimulating hormone (FSH) to prepare eggs in the ovary to mature, and then Luteinising hormone (LH) that triggers the release of the mature egg. It takes about 150 days.

At the beginning of any menstrual cycle, there are generally about 12 eggs that have started to grow. As ovulation (shedding of the egg) nears, one of the eggs that matures first is released from the ovary. It goes into the Fallopian tube (FT) through a receptacle, where it lives for 12-24 hours. If it meets a sperm that is already there, conception is possible. Or, if a woman has sex while the egg is alive and an energetic sperm can reach the egg swimming fast through the uterus (womb) and the FT, taking usually as little as 30 minutes, conception is also possible. The newly fertlised happy egg will travel out of the FT and implant into the uterus 6-10 days later. If the egg misses its bus ie fails to meet with a sperm, it will dissolve and pass out with the menstrual flow.

Though the egg’s lifespan is short, less than a day, the sperm can stay alive, gallivanting like teenagers inside the woman’s uterus and FT from 1-5 days. Woman having sex up to 5 days prior to ovulation can result in pregnancy. Sperms are pampered as refreshment is provided during their short stay by the woman’s cervical fluid.

The egg, literally is quite picky. It will give preference to a smart and healthy sperm with intact DNA. When it finds such a hero it becomes very lovey-dovey. She opens the door by producing a compound that softens its outer layer. Once it has allowed a lover to get inside, it shuts the door by hardening the outer layer, and barring any other suitors hanging around.

Normal cell division is called mitosis, by which the cell divides into two cells, each one receiving a copy of all 46 chromosomes. There is another more complicated cell division called meiosis for sperms in the testicles, and for eggs in the ovary. These are called sex cells as they take part in the differentiation between male and female. Males have two distinct sex chromosomes (XY), while females have two of the same kind of sex chromosomes (YY).

The special cells called sperm or egg contains 23 chromosomes each instead of 46. These 23 chromosomes are not just the replica. During the manufacture of a sperm or the egg, each of its paternal genes physically detach themselves and change places with exactly corresponding bits of maternal chromosome.  This is called crossing over.

Sometimes, two bits coming from two parents may differ eg blue eye colour of the mother and brown eye of the father, when the stronger personality prevails upon the other. In this case, brown eye having stronger personality (dominant), blue eye will be ignored (recessive) in the next offspring, but it will pass on to future generations. Sometimes when two genes are equally stubborn rivals for the same slot they come to a compromises – the body is built in something completely different. These genes are called alleles of each other.

In the Battle of the sexes, Richard Dawkins, the biologist argues that it is misleading to emphasise the disparity between sperm and egg size as the basis of sex roles. Even one sperm is small and cheap [millions get wasted], it is far from cheap to make millions of sperms and successfully inject them into a female against all the competition.

This topic of gender equality brings me to scientists in Melbourne, Australia, where a team at Monash University, has just found out a revolutionary technique, though in its early stage, which could exclude men from the creation of babies, allowing lesbians to have a child. Only that all the babies will be females and perhaps lesbians.