in every living organism nature has the instinct of procreation.But the birth of children - it is not only the maintenance of life on Earth, but also the joy and hope of the parents.The inception of a new life begins at conception Conception, ovarian cycle, fertilization and genetics baby , and all the hazards that have taken place, could have a negative impact not only on fertilization, but also on the capacity for it.To understand the importance of this definition, it is necessary to recall how conception occurs.
stages of conception
formation of the ovum (embryo not yet) consists of several stages:
- formation of the zygote;
- transfer and implantation of the ovum.
starting torque in the mechanism of conception is the maturation and release of an egg, which is called ovulation Ovulation - How to determine as accurately as possible? .Ovulation - is one of the periods of the menstrual cycle, which occurs approximately in the middle.Un
After ovulation has occurred, under the influence of progesterone Progesterone - norm and pathology , which is produced by the corpus luteum, the endometrium starts to change.It thickens, it becomes loose and blood supply.All of these changes are necessary for the adoption of a fertilized egg (implantation).
After the release of an egg has occurred, it tends to get into the fallopian tube where it is moving by pili and cilia located in the inner shell.That should happen here and meeting the egg and sperm.Life is short egg, only 24 hours, and that during this time the sperm need time to reach the fallopian tubes.
fertilization and the formation of the zygote
next stage of conception - a fertilization.The mature egg is fertilized by sperm, which consists of the head, neck and tail, and also carries 23 chromosomes.Generates sperm seminiferous tubules of male sex glands and are part of the seminal fluid (semen).Dimensions of sperm into the egg a few times smaller, and their life span up to three days.Once in the vagina, the sperm are beginning to overcome the cervical mucus cervical Cervical canal - the path traversed by every person , fall into the uterine cavity and move towards the fallopian tubes.An important role in maintaining the activity of enzymes playing sperm contained in the mucus produced by glands of the uterus.With this mucus in the uterus formed a special path on which the most active sperm reach the mouth of the fallopian tube.After reaching the egg, sperm (the survivors, about a few hundred) attached to its shell and begin to dissolve it.And only one, the strongest and sperm motility penetrates the ovum and merges with its nucleus.As a result of the merger of a zygote containing 46 chromosomes.After penetration of the sperm into the egg, it changes the composition of its shell, which prevents the introduction of other sperm.
Moving egg and implantation
Once fertilization has occurred, it begins to divide (first formed two cells, then four, and so on).At the time of crushing the egg moves through the fallopian tube, in order to get to the uterus.At the time of implantation of the zygote already it consists of 64 cells called the blastocyst.Approximately on the eleventh day after fertilization the blastocyst shell ruptures, allocated special substance that melted the functional layer of the endometrium and the fertilized egg attaches to the mucous membrane of the uterus.