The root.
pulp
The pulp is the innermost layer of the tooth that contains nerves, blood vessels, and connective tissue. It is responsible for providing nourishment to the tooth and transmitting sensory information. If the pulp becomes infected or damaged, a root canal treatment may be necessary to save the tooth.
The soft innermost part of a tooth, containing blood vessels and nerves.
The part of a tooth where the nerve and blood vessels are found is called the pulp chamber.
The small pin hole in the first molar is the natural opening of the tooth's root canal, called the apex. This opening allows for nerves and blood vessels to enter the tooth to supply nutrients. It is a normal part of tooth anatomy and does not indicate any problem.
The hard part of the tooth is actually not a living structure. The living structures are the nerves and blood vessels that are inside the tooth.
The apex of a tooth is the tip of the root where nerve and blood supply enter the tooth through the root canal. It is located at the bottom of the tooth, in the area where the tooth meets the jawbone.
The pulp is the soft tissue inside the tooth that carries blood vessels and nerves, supplying the tooth with food and oxygen.
Hyperemia
A section of tissue detached from its blood supply, moved to another part of the body, and reattached by microsurgery to a new blood supply
The cornea, the clear part of the eye, does not contain blood vessels and it receives oxygen supply directly from the air.
Enamel is developed during infancy and adolescence only. Once the tooth has erupted into the mouth, no more enamel is created. Enamel has no innervation and no blood supply. In short, it is not living tissue, and cannot be healed if broken by trauma or disease (tooth decay). In contrast, bone tissue has blood supply and innervation. It continues to replace it's worn out cells throughout life, and it is capable of healing if damaged through injury or disease.