Umbilical cord has
**Core Concept**
The umbilical cord is a vital structure connecting the fetus to the placenta, facilitating the exchange of oxygen, nutrients, and waste products. It contains two umbilical arteries and one umbilical vein, which are responsible for the exchange of substances between the fetus and the placenta.
**Why the Correct Answer is Right**
The correct answer is related to the presence of Wharton's jelly, a gelatinous substance that surrounds the umbilical cord and protects it from compression and damage. Wharton's jelly is composed of mucopolysaccharides and is produced by the mesenchymal cells of the umbilical cord. This jelly-like substance maintains the umbilical cord's structure and function, allowing it to withstand the mechanical stress of fetal movement and maternal uterine contractions.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the umbilical cord does not contain lymphatic vessels. The lymphatic vessels are responsible for draining excess fluid and proteins from the tissues, but they are not present in the umbilical cord.
* **Option B:** This option is incorrect because the umbilical cord does not contain a nerve supply. The nerves are responsible for transmitting sensory and motor signals, but they are not present in the umbilical cord, which is primarily a vascular structure.
* **Option C:** This option is incorrect because the umbilical cord does not have a significant role in the production of red blood cells. The production of red blood cells occurs in the bone marrow, and the umbilical cord is not involved in this process.
**Clinical Pearl / High-Yield Fact**
The umbilical cord typically measures between 50-60 cm in length and has a diameter of 1-2 cm. The presence of a single umbilical artery is a potential risk factor for fetal growth restriction and other complications.
**Correct Answer: D. Wharton's jelly.**