Human development begins through sexual reproduction and the subsequent gametogenesis. A cell called gamete, which was formed from primordial germ cells and has a haploid set of chromosomes, encounters a female egg cell as sperm. After fertilization, the zygote develops, the germ is embedded and the process of embryogenesis begins - the growth of an embryo. The embryology investigates and observes this process.
What is embryology?
This is a branch of medicine and developmental biology. The word “embryon” comes from the Greek and means the fruit of life. It is thus the science of the entire prenatal development.
Already in the 5th century BC First theories were put forward about how an embryo should develop. However, the idea was still shaped by the believing aspect, so the act of divine creation was assumed. The Greek philosopher Aristotle then proposed the theory that sperm might activate the woman's menstrual blood in some way and thus initiate the formation of an embryo. Leonardo da Vinci undertook the first measurements of the various stages of an embryonic development, while in the 2nd century AD the doctor Galenus, who also came from Greece, had written about prenatal development and the placenta, conditions that embryology down to the Shaped modern times.
The fertilization, the development of a fertilized egg cell up to the embryo is examined in more detail here, whereby the embryology can be divided into general and special.
Treatments & therapies
The development of the germ cells plays a role in general embryology. Likewise the process of ovulation, fertilization and implantation. The formation and function of the membranes, placenta and germinal discs are examined more closely. The industrial layers that envelop the fetus in the uterus are called membranes. They eventually form the amniotic sac that separates the embryo from the maternal tissue. In embryology, a distinction is made between the outer and the inner egg shell. The membranes are attached to the edge of the placenta.
The placenta forms in a woman's uterus and continuously supplies the embryo with oxygen and nutrients obtained from the mother's metabolism. It forms after the blastocyst has implanted in the uterus and weighs around 500 grams when fully developed. It consists of a maternal and a fetal part, while the embryo is connected to the placenta via the umbilical cord. The germinal disc, in turn, is the part of the fertilized egg from which the embryo is formed. All of this belongs to the field of general embryology.
The special embryology goes beyond the development of the embryo and focuses more on the development of individual organ systems. Here the formation of the brain, heart, lungs and other organs is examined more closely. The summary then deals with the embryology of the respective organ.
In addition, there is comparative embryology, which contrasts the embryonic development of different species and also draws conclusions about phylogenetic aspects, the descriptive one, which analyzes the development of animal or plant structures, the causal, functional and causal analysis and asks the question of determining factors that influence the development of the embryo, and the phylogenetically oriented embryology, which carries out an analysis of evolution and looks at phylogenetic changes in the processes, which in turn enriches homology research.
Other areas that embryology can influence are immunology, tissue culture, and endocrinology. Then there was the cell fusion and the method of nuclear transfer. Subjects gradually merged, so that z. B. Geneticists, developmental and molecular biologists worked together.
Another area is molecular embryology. This deals specifically with the molecular processes that take place during the embryonic development phase. The mechanisms that control cell differentiation are relevant. It was found that the development of the embryo in animals and humans are similar in terms of a molecular level. It was also found out that genes involved in development play an important role in possible diseases in humans.
Diagnosis & examination methods
If malformations develop or the germ cell is damaged during the development of the embryo, medicine and embryology speak of gametopathy. These are defects that are already present in the egg or sperm cell before fertilization takes place.
A defect that sets in during the development of the fetus is called fetapathy. The first stage of pregnancy is particularly sensitive to harmful effects, while the second two stages are less susceptible, as most of the organs have already formed. Such fetapathies can reach the fetus via the placenta on the bloodstream, can infectious agents, poisons or z. B. be metabolic disorders of the mother.
Science promises u. a. great chances of a cure for diseases that have so far hardly been treated by using embryonic stem cells. To obtain these, human embryos are destroyed at a very early stage, which is why this process is still extremely controversial. While the production of embryonic stem cells is prohibited in Germany, such tests have already been carried out in America and Great Britain. B. in patients who suffered from the disease "Stargardt's disease". Embryonic stem cells can transform themselves as body cells into any kind of tissue and thus replace diseased cells. Embryonic stem cells were placed in the eyes of the test subjects to test whether they were compatible with the damaged retina. The result was positive.
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