During the normal nine months of pregnancy, the fertilized egg develops in a series of phases known as prenatal developmental stages.
The three stages of prenatal development are as follows:
- The pre-embryonic phase of intrauterine development, also known as the “germinal phase”, lasts from fertilization to the second week.
In this period of time, the fertilized ovum (known as a zygote) descends through the fallopian tube until it reaches the uterus.
During this process, the zygote repeatedly self-replicates, leading first to the morula and later to the blastula.
- Embryonic stage (From the third week of gestation the embryo is known as gastrula)
The cell layers of the blastula have differentiated to the point of giving rise to the three structures from which the baby's body will form: the ectoderm, the mesoderm, and the endoderm.
The development of the fundamental structures of the body continues and is consolidated.
It is the longest stage of intrauterine development, spanning from the ninth week to the time of delivery.
Therefore, we can conclude that the three stages of prenatal development are: pre-embryonic, embryonic, and fetal.
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