Ligamentum teres is formed after :
**Core Concept**
Ligamentum teres is a fibrous remnant of the umbilical vein, which plays a crucial role in fetal circulation. In the fetus, the umbilical vein carries oxygenated blood from the placenta to the fetus, and it is an essential part of the circulatory system.
**Why the Correct Answer is Right**
The ligamentum teres is formed after birth when the umbilical vein obliterates and transforms into a fibrous cord. This process occurs due to the decrease in blood flow through the umbilical vein after birth, leading to fibrosis and subsequent obliteration. The ligamentum teres remains as a fibrous remnant of the umbilical vein.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the formation of the ligamentum teres.
**Option B:** This option is incorrect because it is not related to the formation of the ligamentum teres.
**Option C:** This option is incorrect because it is not relevant to the formation of the ligamentum teres.
**Clinical Pearl / High-Yield Fact**
The ligamentum teres is an important landmark in the abdominal cavity, and its presence can be used to identify the location of the umbilicus. In addition, the ligamentum teres can be used as a landmark for surgical procedures in the abdominal cavity.
**Correct Answer:** C. After birth.