At day 7-8 postconception, the blastocyst has completely crossed the epithelium and is embedded within the endometrium. The developing embryo is completely surrounded by the growing placenta, which at that stage consists of the two fundamental subtypes of the tro-phoblast. The multinucleated syncytiotrophoblast is in direct contact with maternal tissues, while the mononu-cleated cytotrophoblast as the stem cell layer of the trophoblast is directed towards the embryo.
All of the differentiation and developmental stages of the placenta described so far take place before fluid-filled spaces within the syncytiotrophoblast can be detected. This is why this stage is termed prelacunar stage.
Was this article helpful?
The first trimester is very important for the mother and the baby. For most women it is common to find out about their pregnancy after they have missed their menstrual cycle. Since, not all women note their menstrual cycle and dates of intercourse, it may cause slight confusion about the exact date of conception. That is why most women find out that they are pregnant only after one month of pregnancy.