"I would like to tell you that the process of the sperm meeting the egg is like the old dating show blind date. Unfortunately, it is more like Forest Gump’s box of chocolates; you never know which one you are going to get. Now things are going to get a little technical here but stay with me. It is in the fine details of this process that the beauty of life is found."
I am one of 4 siblings. This is code for a life of having a predator-prey relationship when it comes to mealtimes; the remote for the TV; anything nice being left in the fridge; and the infamous battle for the front seat of the car: the true testament of the alpha. Growing up it was just my older brother and me for around 8 years. Our early years in Ghana were filled with adventure, it was me and brother against the world. We would buy sachets of ideal milk or nido powder; eat choco milo cubes and our personal favourite sugar water. Yeah, I said it, sugar water. When we were growing up all you needed was an ice-cold glass of water and a couple of tablespoons of sugar. That was the life. Time passed and our crew grew strong, we gained womb mates. (Do you get it, womb mates…(insert laughter)). With more kids, it was easier to get away with stuff, mwahaha; I mean they never got in that much trouble. Sorry kids. Any way… just to think, this life-time of endless fun and bants, began with 2 cells meeting. Sperm, meet egg.
I would like to tell you that the process of the sperm meeting the egg is like the old dating show blind date. Unfortunately, it is more like Forest Gump’s box of chocolates; you never know which one you are going to get. Now things are going to get a little technical here but stay with me. It is in the fine details of this process that the beauty of life is found.
"The journey to the egg is set to wean out the weak sperm and only the strong survive. In the words of TLC, we don’t want no scrub"
In the last blog post, we discussed the menstrual cycle. We now know that during ovulation the oocyte (an immature egg) is released from the follicle within the ovaries. Once released from the ovaries, the egg rests in the fallopian tube whilst also slowly migrating towards the nucleus. During intercourse, each sperm released from the male is poised and ready to fertilise the egg. However, the journey to the fallopian tube for one of the smallest cells in the body is a treacherous one. The journey to the egg is set to wean out the weak sperm and only the strong survive. In the words of TLC, we don’t want no scrub. It’s a common misconception that it is the fastest sperm that meets the egg; well it’s a yes and no situation. It is more important for the sperm to be swimming in the right direction i.e. towards the fallopian tube, than to be swimming quickly in the wrong direction.
"Only one sperm must fuse with the egg. Not just because, we like monogamous relationships"
As the sperm draws nearer to the fallopian tube, the egg releases chemo-attractants to signal the sperm to its-self. This is where the magic happens. Only one sperm must fuse with the egg. Not just because, we like monogamous relationships, but because only one set of chromosomes should be inherited from the mother's egg and the father's sperm. Problems may arise if multiple sperm fuse with the egg. This is called polyspermy, and it can lead to dysfunction down the line. Let us zoom in further into this process.
"Now 2 have become 1"
Once the sperm is close to the egg, it lingers around until its sperm head has been degraded to release the specific enzymes needed to penetrate the protective outer layers of the egg. The sperm has to pass through the Granulosa Cells, which form the eggs outermost layer called the Corona Radiata. The sperm then docks at the sperm-specific receptors of the Zona Pelucida. This interaction triggers an influx of calcium ions into the sperm head, which in turn triggers enzymes needed for the acrosomal reaction within the sperm head. These enzymes allow the sperm to degrade the Zona Pelicuda until it reaches the membrane of the egg. The #goals of all sperm at this point in the game is to be the first sperm to dock into the sperm receptors within the membrane of the egg. Once a sperm does this, it is all over for everyone else. This binding triggers the fusion of the sperm head with the egg. As this is happening calcium is released from the egg, which causes the removal of remaining sperm binding proteins in the membrane of the egg and the Zona Pellucida. This stops any other sperm from fertilising the egg.
Now 2 have become 1. This is quite cool when you think about it. Your body will reject anything foreign to it. I mean it has a whole border force and an army ready to defend its territory against any perceived threats. If you don't believe me, please ask someone to hayfever, they will tell you how overprotective their immune system is. This is a great image of what I believe was Gods great design in marriage. These cells do not just share common borders, they don’t coexist, or co-cooperate with one another, but they essentially give all they are to one another. It is this oneness which is the beginning of life.
At the point of fertilisation, the baby’s genetic makeup is complete. It has all the instructions to produce everything it needs from fingernails to the protein that gives their hair a particular curl. At the point of fertilisation, the gender of the baby is also determined. Unlike the egg, the sperm cells can either carry the sex chromosomes X or a Y. So it is the sperm that determines the gender of the baby.
The fertilised egg rapidly splits within itself to form a ball of cells within the original egg shape. It remains in the fallopian tube as it grows in cell number and migrates to the uterus. The story gets better! Once in the uterus, the process of implantation occurs. Implantation is essentially like planting a seed in the soil, only this time, the ball of cells now called a blastocyst is being buried into the wall of the uterus a.k.a. endometrium. A whole list of structures and events occur after this point including the formation of the placenta a.k.a. an ingenious architectural and engineering feat. Also the development of the nervous system and other vital systems in the body. You end up with one cell doing a transformation greater than anything seen on 'stars in their eyes'; going from one cell to a fully-fledged human being. Yes, you read that correctly, from a cell to a functioning organism.
I don’t think I can look at my siblings in the same way. Their life is nothing short of a miracle. To think, this person I fight over the TV with was once a rapidly developing ball of cells in my mother's womb. 2 cells becoming 1 shows us that we were made to be whole. You were not created or designed from a place of the deficit but with everything we need in mind.
See you on the next post.