Pregnancy and placenta formation

Introduction

Pregnancy is one of the wonderful experiences in one`s life. In human beings, it is a very intricate but physiologically important process. A healthy pregnancy accounts for a period of 9 months, 7 days and it is divided into 3 trimesters; the first trimester in the first 3 months from the time of conception and the second trimester is in between 4-6 months of pregnancy and the rest of the period(7-9 months) is the third trimester. During pregnancy, a woman experiences a lot of hormonal, anatomical and physiological adjustments within her body. One such change is the formation of the placenta. This article is meant to delineate the formation of the placenta during the pregnancy

 

Formation and development of the placenta

The placenta is the junction between the mother and the growing hence, it acts as a bridge between the baby and the mother. Placenta assists in many functions. Firstly, it attaches the developing fetus to the mother`s uterine wall through the umbilical cord. The blood supply to the placenta allows nutrient uptake, regulation of body temperature of the baby, elimination of wastes and carbon dioxide gas. The placenta is also instrumental in fighting against foreign invaders such as bacteria, virus and much other materials to ensure the growing fetus is safe.  One of the major functions of the placenta is the production of pregnancy-related hormones and their regulation. As the placenta grows, it forms tiny hair-like villi. These villi develop branched-like roots that penetrate the decidua( inner uterine wall) so that the embryo is firmly attached to the mother. A typical placenta has 2 surfaces, namely, maternal placenta and the fetal placenta. The maternal surface is a junction between the umbilical cord and mother whereas the fetal surface is the junction between the umbilicus and the placenta. Placenta is the most vital component of pregnancy for both the mother and baby.  It helps to trap a number of toxic chemicals so that the growing baby is safe inside. It also helps in metabolizing a number of substances so that they are released the fetal circulation. The placenta is a temporary structure as it will be expelled out at the time of the birth of the baby. The formation of the fetus commences upon the implantation of the blastocyst. The blastocyst is the early phase of embryonic development where a mass of undifferentiated cells are formed after the fertilization. The external layer of the blastocyst becomes the trophoblast. The trophoblast is modified into an outer layer of the placenta. The outer layer is further divided into 2 layers, namely, the underlying cytotrophoblast layer and the overlying syncytiotrophoblast layer. Layers are formed based on the cellular differentiation and fusion of the underlying cytotrophoblast cells.  The development of the placenta is a continuous process throughout the pregnancy however, the development of the maternal side is completed by week 14.

 

Placenta attached to umbilical cord-image from google

 

 



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