<span>Epithelial tissue is densely packed cells that used most in the area where protection is needed. This cells mostly used in skin, some with more keratin which will increase their ability to protect. In bone, the main protective layer is calcium mineral which was deposited by osteocytes. Because this bone doesn't really need more epithelial cells. Bone tissue only needs a good vascularization and connective tissue to support it.
</span>
Uh, can you be more specific? Theory and belief of what?
The air can be considered polluted once harmful or toxic substances are being released and introduced into the air and can bring many types of diseases or health problems to the living organisms in it. Some actions can be done in order to remedy air pollution and these include: government passing regulatory laws, testing for car emissions and carpooling so there will be less driving.
A: provided structural support to the cell