Pregnancy and placenta formation


Pregnancy is one of the wonderful experiences that every species undergo. In human beings, it is a very complex and physiologically significant process. A healthy and normal pregnancy has a time period of 9 months, 7 days. Pregnancy is divided into trimesters; the first trimester is the first 3 months from the time of conception and the second trimester is in between 4-6 months and the rest of the period is called the third trimester. During pregnancy, a woman undergoes a lot of hormonal, anatomical and physiological modifications within herself. One such change is the formation of the placenta.

Table of Contents

1. Introduction

2. Formation and development of the placenta

Formation and development of the placenta

Placenta is the junction between the mother and the growing fetus inside the mother`s uterus. It acts as a bridge between the baby and the mother. Placenta serves many functions. It connects the developing fetus to the mother`s system 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. Placenta also helps in fighting against foreign invaders such as bacteria, virus and many other material.  One of the major functions of the placenta is, hormones production and regulation necessary for pregnancy. As the placenta grows, it forms tiny hair-like villi. These villi get branched to form roots that penetrate the decidua( inner uterine wall). A typical placenta has 2 surfaces, namely, maternal placenta and the fetal placenta. The maternal surface is a junction between the umbilical cord and the fetal side. Placenta is the most vital part of pregnancy for both the mother and baby.  It helps to trap a number of toxic chemicals so that the growing baby us safe. It also helps in metabolizing a number of substances which in turn release the metabolic products into maternal or fetal circulations. The placenta is temporary because it will be expelled from the body at the time of the birth of the fetus. The formation starts upon the implantation of the blastocyst inside the maternal endometrium. The external layer of the blastocyst becomes the trophoblastic that forms itself into the 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 cord-image from google




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