Lecture : Human and Vet placenta formation
Document Summary
The connecting stalk (which will become the umbilical cord) and the chorionic plate produce blood vessels as well. The circulation of the foetus is now connected to the circulation of the mother. The placenta is a tissue fusion, not a blood vessel. Except for blood, all maternal tissue is lost. Because foetal and maternal cells are separated by thick cell layers, antibodies are not transferred to the foetus. The foetus is surrounded by the amniotic cavity. The amniotic cavity grows in size over the next few weeks. The amnion and chorionic plate merge, and the chorionic cavity shrinks. A portion of the yolk sac is incorporated into the embryo to produce the gut tube. A provisional placenta (choriovitelline) is formed by the external component. Chorion is the outermost embryonic tissue and is linked to the uterus" endometrium. Chorionic villi extend into the endometrium, bringing foetal blood into close proximity to maternal blood.
