List the structures contained in the dermis layer of the skin.

The dermis layer of the skin contains several structures, including:

1. Blood Vessels: These are responsible for supplying nutrients and oxygen to the skin. They also help in temperature regulation.

2. Sweat Glands: These glands produce sweat, which helps in cooling the body and excreting waste products.

3. Sebaceous Glands: These glands produce sebum, an oily substance that helps to keep the skin moisturized and protected.

4. Hair Follicles: These are the structures from which hair grows. They are also associated with sebaceous glands.

5. Nerve Endings: These allow the skin to sense touch, temperature, and pain.

6. Collagen and Elastin Fibers: These provide strength and elasticity to the skin.

7. Lymphatic Vessels: These help in the removal of waste products and in the immune response.

8. Fibroblasts: These cells produce collagen and elastin, the proteins that give the skin its strength and elasticity.

9. Mast Cells: These cells are part of the immune system and are involved in the body's response to injury and infection.