In this week's the hormone hCG passes into the maternal blood, so that it is possible to take a pregnancy test and it produces the implantation of the baby, that is the set of physical and chemical processes by which the blastocyst establishes an intimate contact with the mucosa of the uterus.
Expert: Texts of embryology, human
This process begins around 6 or 7 days after fertilization, ending the day 12 of gestation and thanks to the secretion of a hormone called progesterone, which prepares the mucosa of the uterus for the implantation, inducing an increased glandular development and to sensitize the mucosa to the contact with the blastocyst.
The implementation can be divided into 2 stages:
Contact: Approximately 6 or 7 days after it has occurred ovulation when the endometrium is in phase progestational and their secretions have formed a film of mucus that covers the walls of the uterus, the blastocyst adheres firmly to the surface of the uterine epithelium.
Penetration: The blastocyst penetrates the compact layer of the endometrium and undergoes intense proliferation, rapidly increasing its size and keeping a definite orientation.
The stage of penetration in the human being is characterized by being highly invasive, during which around 12 days after ovulation, the blastocyst is entirely included in the thickness of the mucosa of the uterus.
During implantation, the blastocyst grows and is able to acquire an organizational structure increasingly complex.
The uterus, as a response to the ovarian hormones, estrogen and progesterone, produces various chemical compounds and growth factors that cause cell proliferation and differentiation, occurring in the endometrium, the conformational changes necessary to allow for normal implantation.
This week starts the circulation, uteroplacental, which allows the flow of the maternal blood, leaving the disposal of the embryo, its nutritive substances and oxygen, thanks to the communication of branches of arterial and venous blood vessels of the maternal, establishing the blood circulation.
In the endometrium passes oxygenated blood to the baby from the spiral arteries, and removes deoxygenated blood through the veins endometrial.
The oocyte human is poor in nutrients and therefore requires an external source for your nutrition, represented by the mother. During embryonic development, from the state of the morula, the embryo uses 3 types of food in succession, provided by the mother.
Milk uterine: it consists of the secretion from the tubes, and the mucosa of the uterus, rich in carbohydrates, lipoproteins and other nutrients that the embryo takes advantage in the early stages of development. In the states of morula late and blastocyst pre-implantation, constitute the food of the embryo, during its journey through the uterine horn and its arrival in the uterus, until the beginning of the implementation.
Histotrofo: corresponds to the remains of tissues resulting from the lysis of the endometrium associated with the implementation, which constitute the food of the embryo at this period, before the establishment of a placenta functioning.
Hemotrofo: is maternal blood, provided by the placenta, which performs the exchanges of metabolic maternal-fetal, until the term of gestation.