The study of embryology and fetal development is an essential component of the Obstetric Nursing course. Embryology is the science that studies the development of embryos, while fetal development refers to the period extending from the ninth week of gestation to birth.
Embryology
Embryology begins with fertilization, the process by which the father's sperm and the mother's egg combine to form a zygote. This zygote then divides to form an embryo, which develops in several stages.
The first stage is the blastocyst phase, which occurs in the first 5 to 6 days after fertilization. During this phase, the embryo is a rapidly dividing ball of cells. The inner part of the blastocyst will become the embryo, while the outer part will become the placenta and umbilical cord.
The next step is gastrulation, which occurs in the second week after fertilization. During this phase, the embryo transforms from a ball of cells to a three-dimensional structure. This is accomplished through the process of cell folding and movement, which forms three layers of cells: the ectoderm, mesoderm, and endoderm. Each of these layers will give rise to different parts of the body.
Ectoderm develops in the nervous system, skin, and skin appendages. The mesoderm will become the cardiovascular system, bones, muscles and the urogenital system. The endoderm will form the gastrointestinal tract, liver and pancreas.
Fetal Development
Fetal development begins in the ninth week after fertilization and continues until birth. During this time, the embryo, now called a fetus, undergoes a series of changes and developments.
By the ninth week, the fetus is about 2.5 cm long and weighs about 2 grams. The heart, which now has four chambers, is beating. The eyes are starting to develop, as are the ears and lips. The arms and legs are stretching and the fingers and toes are forming.
By the 20th week, the fetus measures about 25 cm in length and weighs about 300 grams. The fetus can hear and respond to sounds. The eyes may move and the eyelids may blink. The fetus can also kick, turn and move around inside the uterus.
By the 30th week, the fetus is about 38 cm long and weighs about 1.3 kg. The fetus continues to grow and develop, gaining weight and accumulating fat. The brain is developing rapidly and the lungs are starting to produce surfactant, a substance that helps the lungs expand after birth.
By the 40th week, the fetus is fully developed and ready to be born. The fetus measures about 50 cm in length and weighs about 3.5 kg. Most organs and systems in the body are fully formed and functioning.
In summary, embryology and fetal development are complex and fascinating processes that involve a series of changes and developments. The study of these processes is essential to understand the health and development of the fetus, as well as to identify and treat possible problems or complications during pregnancy.
