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FETUS with PLACENTA

Female Genital Tract

FETUS with PLACENTA
The fetus and placenta are two of the most critical components of pregnancy, with each playing a unique role in ensuring a successful gestation. Let's explore their structure and function in detail.
Fetus
The fetus is the developing offspring from the 9th week of pregnancy until birth. Before the 9th week, the developing baby is called an embryo.
Developmental Stages of the Fetus:
• Early fetal development (weeks 9-12): The organs and structures begin to form. The fetus is about 3 inches long and weighs about 1 ounce. Early in this phase, the heart begins beating, and the face starts to take shape.
• Mid-pregnancy (weeks 13-24): This period is marked by rapid growth, with more organ systems maturing. By the end of this stage, the fetus can begin moving, and the bones harden.
• Late pregnancy (weeks 25-40): The fetus grows rapidly and gains weight. The organs become fully developed, and fat accumulates under the skin. The fetus begins to position itself for birth, with many reaching a head-down position.
Key Features of the Fetus:
• Size: At 12 weeks, the fetus is around 3 inches (7.5 cm) long. By the end of pregnancy, the average fetus is about 19-21 inches (48-53 cm) long.
• Movement: Between 16-25 weeks, the mother may feel the fetus' movements, known as "quickening."
• Senses: By the second trimester, the fetus has developed basic senses such as hearing (able to hear sounds) and taste (through amniotic fluid).
• Heart and Circulation: The fetal heart is fully formed early on and circulates blood through the placenta for nutrient and gas exchange.
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall, facilitating nutrient, gas, and waste exchange. It plays an essential role in maintaining pregnancy.
Structure of the Placenta:
1. Placental disc: The placenta has a circular or disc-shaped appearance and is located on the uterine wall. It is made up of both fetal and maternal tissue.
o Fetal side: The fetal side of the placenta is covered by the amniotic membrane and contains numerous villi (finger-like projections). The fetal blood vessels travel through these villi, where gas exchange and nutrient transfer occur.
o Maternal side: The maternal side of the placenta is where the villi come into contact with maternal blood vessels. It appears more spongy, with red or maroon coloring.

2. Umbilical cord: The umbilical cord connects the fetus to the placenta and contains three blood vessels:
o Two umbilical arteries that carry deoxygenated blood from the fetus to the placenta.
o One umbilical vein that carries oxygenated blood from the placenta to the fetus.
3. Amniotic sac: Surrounding the fetus and placenta, the amniotic sac contains amniotic fluid, which cushions and protects the fetus and helps maintain an even temperature.
Functions of the Placenta:
• Nutrient and Oxygen Exchange: The placenta allows oxygen and essential nutrients (like glucose, amino acids, and fatty acids) from the mother’s blood to pass to the fetus, and waste products like carbon dioxide and urea to pass from the fetus to the mother’s blood.
• Hormone Production: The placenta produces several hormones that are crucial for maintaining pregnancy. Key hormones include:
o Human Chorionic Gonadotropin (hCG): Maintains the corpus luteum, ensuring continued progesterone production in early pregnancy.
o Progesterone: Maintains the uterine lining and prevents contractions.
o Estrogen: Stimulates uterine growth and blood flow.
• Immunological Protection: The placenta acts as a barrier to protect the fetus from infections and provides passive immunity by transferring antibodies from the mother to the fetus.
• Waste Removal: Metabolic waste products from the fetus, such as urea and carbon dioxide, are transferred back into the mother's blood for excretion through her kidneys and lungs.
Placental Abnormalities:
• Placenta Previa: A condition where the placenta is located low in the uterus, potentially covering the cervix, which may lead to complications during delivery.
• Placental Abruption: When the placenta detaches prematurely from the uterine wall, causing bleeding and fetal distress.
• Placenta Accreta: When the placenta grows too deeply into the uterine wall, which can complicate delivery.
Relationship Between Fetus and Placenta:
The fetus relies entirely on the placenta for sustenance, oxygen, and waste removal. The placenta not only provides the necessary nutrients but also plays an active role in the fetal development process, ensuring that the fetus can grow and mature in a protected environment. The exchange of substances between the fetus and placenta is essential for normal development.

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