FERTILIZATION, PREEMBRYO and FETUS
FERTILIZATION, PREEMBRYO AND FETUS
The human race keeps surviving because of the procreative ability of man. The reproductive gametes are haploid in nature. Therefore, humans need their opposite sex in order to have their offspring.
When the male and female gametes come in contact and fuses together an important action has taken place. This is am important stage in reproduction. This juxtaposition of two opposite gametes is what is called fertilization. In fact this is when a woman conceives, though the fertilized egg still needs to be implanted on the wall of the uterus {womb}. Fertilization is therefore what men and women try to attain through many ways, since technology has make it possible to be pregnant through other ways rather than the convectional way of relying on sex.
After fertilization, a period of 14 days that follows is referred to as the pre-embryonic development period. During this period the fertilized egg, becomes a single cell and also divides in order to produce more cells. In the first four to five days the cell divides to form clusters of cells. The cluster of cells will be a hollow sphere shape smaller than a pin head, having an inner cell mass and outer layer of cells. At this stage of pre-embryonic period we normally call that cluster blastocyst. The inner cell mass will develops to become the baby.
The next stage after fertilization, which is still in the pre-embryonic stage is the implantation of the blastocyst in the uterus. This happens about a week after the fertilization. During this period the blastocyst attaches itself to the womb and constructs one of the most important links that it needs for its survival – – – – the placenta. The placenta of the pre-embryo will enable it to have food and oxygen from its mother. Here it also releases its wastes.
In about the ninth day after fertilization, there will be about 20 cells. A restructuring will takes place. This restructuring and differentiation takes about five days to create the structure biologist actually refers to as embryo. So the first two weeks after fertilization is refers to as embryo
Following this pre-embryonic period, after fertilization is called embryonic development period. At this time the unborn is refer to as an embryo. It will still be referred to as an embryo till the eighth month of the pregnancy. But after the eighth month, the unborn is will be called a fetus.
