The kind of epithelium which forms the inner walls of blood vessels is squamous epithelium.

The inner walls of blood vessels, also known as the endothelium, are lined with a specific type of epithelial tissue called squamous epithelium. This type of epithelium is composed of thin, flat cells that are arranged in a single layer. The cells are tightly packed together, forming a smooth and continuous lining along the inner surface of the blood vessels.

Function of Squamous Epithelium in Blood Vessels:
The squamous epithelium in blood vessels serves several important functions, including:

1. Barrier Function: The thin and flat cells of squamous epithelium provide a barrier between the blood and the surrounding tissues. This barrier helps to regulate the exchange of substances, such as oxygen, nutrients, and waste products, between the blood and the surrounding tissues.

2. Smooth Surface: The smooth surface of squamous epithelium allows for the smooth flow of blood through the blood vessels, reducing friction and facilitating the movement of blood.

3. Selective Permeability: The squamous epithelium selectively regulates the passage of substances across the blood vessel walls. It allows certain molecules, such as oxygen and nutrients, to pass through while preventing the leakage of larger molecules, such as proteins and blood cells.

Other Types of Epithelium:
While squamous epithelium is the predominant type of epithelium in the inner walls of blood vessels, other types of epithelium can also be found in different regions of the body. These include:

1. Cuboidal Epithelium: Cuboidal epithelium consists of cube-shaped cells and is found in the lining of small ducts and tubules, such as those in the kidney and certain glands.

2. Columnar Epithelium: Columnar epithelium is composed of tall, elongated cells and is found in the lining of the digestive tract, respiratory tract, and reproductive organs.

3. Ciliated Columnar Epithelium: Ciliated columnar epithelium is columnar epithelium with cilia on its surface. It is found in areas of the respiratory tract and female reproductive tract, where the cilia help to move mucus and facilitate the movement of eggs.

In conclusion, the inner walls of blood vessels are lined with squamous epithelium, which provides a smooth surface, acts as a selective barrier, and allows for the exchange of substances between the blood and surrounding tissues.