Fetal Development

6 Pages 1599 Words

Before human development can begin fertilization, the fusing of the sperm and the egg in the fallopian tube, must occur for it to become a zygote. The developing embryo, is called a zygote at this stage, floats down the fallopian tube towards the uterus.
The first week of development is called the period of cleavage. Shortly after fertilization
the zygote cleaves into 2 cells then to 4 cells, 8 cells and so on. Around the third day it’s about 16 cells, it is called a morula. Once in the uterus, the developing embryo, called a blastocyst
searches for a nice place to implant ,where it burrows beneath the surface of the uterus.
The second through the eight week of development mark the embryonic phase E arly in
the phase the cells of the embryo begin to split into three different cells ,the endodoerm and the
ectoderm form first and then the mesoderm forms in between. These layers will form all of the
body organs. The ectoderm, will from the nervous system, the skin , and the lining of the mouth
and anal canal; The mesoderm will form the muscle, bones the cardiovascular system, and the
reproductive system; and the endoderm will form the digestive tract, respiratory tract and the
urinary tract.
The unborn child is only one-sixth of an inch long, but developing rapidly . The backbone,
spinal column and nervous system are forming. The kidneys, liver and intestines are taking form.
By day 21 the embryos tiny heart has begun beating. The yolk sac, produces blood cells that
form on the underside of the embryo. As the embryo becomes cylindrical in shape, the amnion,
which contains amniotic fluid, encloses the embryo cushioning it in amniotic fluid. The yolk sac
and other tissues on the embryos underside are gathered in this process and becomes the
Umbilical cord, which extends from the umbilicus of the embryo into the placenta and is
important in the vascular relationship between mother and embryo . the embryo receives
nut...