What is fertilization?
The fertilization of a woman’s egg cell by sperm from a man requires many basic conditions which must be fulfilled for the fertilization process, but it is also divided into several individual steps. For this reason, human reproduction is a highly complex and therefore very susceptible to disruption. Not only a proper maturation of both egg cells and sperm is essential for fertilisation, but also the time of unprotected sexual intercourse and the anatomical conditions of both female and male reproductive organs play a decisive role in egg fertilisation.
Procedure of fertilization
The female menstrual cycle is subject to a relatively large time span and can normally last between 25 and 35 days. In the following, the frequent 28-day cycle is used as an example. In the first fourteen days of the cycle, counting from the first day of the period, the ovarian follicles mature under hormonal control.
As a result, individual oocytes become larger, although usually only one dominant oocyte is actually ready to jump, thanks to a selection mechanism. Around the fourteenth day, ovulation occurs. This causes the dominant follicle to burst and the egg is released from the ovary into the free abdominal cavity for a brief moment.
From there, the egg reaches the fallopian tube, the most common site of egg fertilisation, via the fimbrial funnel located in the immediate vicinity. In the course of sperm production, the so-called spermatogenesis, the man produces mature sperm in several individual steps. This process, which takes about 65 days, normally results in the creation of healthy and motile sperm.
Up to 600 million sperm reach the female body via the sperm which is released into the woman’s vagina during sexual intercourse during the man’s sexual climax. Via the vagina, the sperm rise into the uterus, from where they enter the fallopian tube. The vast majority of the sperm die on the way, the rest undergo another maturation process essential for fertilisation.
On the one hand, the sperm wall becomes thinner and on the other hand, the sperm motility is increased. Both facilitate the penetration of the egg cell membrane. In the fallopian tube, the sperm then penetrate the egg cell.
This process is only possible for a short period of time, because after ovulation, the egg cell can be fertilised for a maximum of 24 hours. Subsequently, during the so-called conjugation, the cell nuclei and thus the chromosome sets of the sperm and the egg fuse. The zygote is created, a cell capable of development and division, which then migrates to the uterus via numerous division processes in order to implant itself there.
