Nidation refers to the implantation of a fertilized egg into the lining of the uterus. This continues to develop into the placenta to nourish the egg following nidation. From the time of nidation, the woman is considered pregnant.
What is nidation?
Nidation refers to the implantation of a fertilized egg into the lining of the uterus. Fertilization occurs as an egg travels from the ovary to the uterus, usually happening in the fallopian tube. Late fertilization can still occur after the egg has been accepted in the uterus. During the maturation of the egg, the mucous membrane of the uterus has thickened, preparing for fertilization. A sufficiently thick mucosa is a prerequisite for nidation. The egg is much larger than a sperm because it must be able to feed itself for a while. After fertilization, its resources are almost all used up, but right now it needs the energy for the upcoming cell divisions. It gets this through nidation, which connects it to the supply system of the woman’s body. For this purpose, the egg sits on the surface of the uterine mucosa and is absorbed and enveloped by it. The mucous membrane forms blood vessels that lead to the fertilized egg in order to supply it with dissolved nutrients. In this way, thanks to nidation, it can continue to live even though its own energy resources are already depleted. Following the nidation that has taken place, the woman is considered pregnant because now the embryo develops and in most cases the egg does not die.
Function and task
An egg on its own can only sustain itself for as long as it takes to travel from the ovary to the uterus. If it is not fertilized, it dies because it no longer has any energy or use. A fertilized egg, on the other hand, must go through several cell division processes and develop from a single cell into an entire embryo with a multitude of cells. It cannot accomplish this with its own energy resources, which are nearly exhausted, and the sperm cannot supply it with the energy it needs either. What it needs is energy from the mother’s body. Therefore, the endometrium is intended for nidation, because this tissue is capable of forming a supply organ that only develops during pregnancy: the placenta. After nidation, the existing mucosal tissue gathers in one place and forms blood vessels to supply the egg. The placenta, which begins to develop immediately after nidation, supplies the embryo for nine months and is then shed at birth. The first step in the development of the placenta is nidation. At the same time, nidation means a change in hormonal balance, as the body now recognizes that the egg has been fertilized and a pregnancy exists. Soon after the successful nidation of the egg, the first physical signs of pregnancy occur.
Diseases and ailments
Nidation itself is a relatively simple process that, in itself, occurs without error in most cases. However, the lining of the uterus may not be thick enough for nidation and it may fail because of this. Other problems with the uterine lining, such as endometriosis, are also capable of preventing nidation and therefore pregnancy. Most often, such difficulties have hormonal causes or diseases such as endometriosis, which involve changes in the mucous membrane texture and spread. Since nidation often cannot then take place, affected women cannot become pregnant without help. Even completely healthy women can develop a so-called ectopic pregnancy, which is associated with nidation. In this case, the egg does not nest in the uterine lining as intended, but remains in the fallopian tube after fertilization or develops elsewhere in the abdomen outside the uterus. Ectopic pregnancies can be dangerous because the egg usually dies and releases toxins that can be life-threatening to the woman. There is a threat of blood poisoning if it is detected too late. Extremely rare is nidation outside the uterus, from which an embryo nevertheless forms. In these cases, the baby actually develops in the mother’s abdomen.Under certain circumstances and with constant medical supervision, such a baby can be carried to term, but not born naturally. Nevertheless, such a defective nidation causes a great health risk for the mother, since the internal organs have no protection from the baby. Whether the baby will be born viable and healthy is also not guaranteed. In cases of faulty cell division after nidation, the already fertilized egg is rejected by the woman’s body and excreted as a hemorrhage – sometimes unnoticed. If the child were viable, the pregnancy would remain after nidation, but the child would then be born with a disability.
