Organisms have the amazing ability to beget new life. In bacteria, this can be as simple as splitting itself in two. In humans, however, this process is much more complex.
As a sexually reproducing animal, both a man and a woman are required for the creation of a new person. The process, as complex as is it, is so intricately designed by nature that it could possibly be considered as one of the greatest abilities of the human body.
A man contributes sperm, providing half of the genetic material the future baby. The sperm also decides the sex, depending on whether it carries the X or Y chromosome. Note that gametes only carry half the number of chromosomes (which are usually paired) of a normal cell.
Sperm is made in the testes. Here, under the guidance of hormones such as testosterone and nurturing cells, they grow from a small stem cell, into a plump, round spermatocyte, until it is streamlined to become the sleek spermatozoa that people are more familiar with. All of this occurs as the cell journeys from the outside of the seminiferous tubule to the centre where it is released altogether with its fellow batch.
The sperm is still immature, the equivalent of a high-school graduate. It is expelled into the epididymis, a 4-metre-long tube packed full of concentrated sperm, acting as the “boot camp”. Here, the sperm is drained of extra baggage it is carrying, while learning how to swim effectively. It is stored until the time comes.
A woman contributes an egg, carrying the other half of the genetic material required. It is significantly bigger than a sperm, and as such is produced in much fewer numbers. A woman, unlike a man, has a limit to how many eggs she can produce, and the moment her reservoir runs out is called menopause. Until then, she produces one (or more sometimes) egg every month according to her menstrual cycle.
An egg is developed within a follicle, that acts as a house and oestrogen factory until the egg is released. To get to this stage, it needs to defeat its competitors first. To prevent multiple pregnancies, the ovaries kill all secondary follicles except one dominant follicle. The follicle then ovulates, wherein the oocyte (egg) is expelled almost explosively, caught by the finger-like fimbriae, and then transported towards the uterus via the fallopian tube.
If the egg is not fertilised within a day, it dies and is later expelled with the endometrium, in what every woman knows as a period.
This is only the beginning of the long journey until the miraculous birth of a child.
(Full series here: https://jineralknowledge.com/tag/arkrepro/?order=asc)