By measuring telomeres, some scientists believe they can determine biological age, which doesn't always equal chronological age. That means some people may be biologically older or younger than their age, said Jerry Shay, professor and vice chairman of cell biology at UT Southwestern Medical Center in Dallas.
It is of ectodermal origin and is continuous with the skin at various body openings such as the eyes, ears, nose and mouth, the urethral opening and the anus. Some mucous membranes secrete mucus, a thick protective fluid. The function of the membrane is to stop pathogens and dirt from entering the body and to prevent bodily tissues from becoming dehydrated.
Mucous membranes line all body cavities that open to the exterior of the body. They line the digestive, respiratory, urinary and reproductive tracts. The epithelium varies depending upon the location. The underlying connective tissue is areolar and is called lamina propria. Mucous membranes are kept wet either by secretions or the fluids which they contain. Their name is derived from thick, viscous secretion, mucus, that is secreted onto the surface of most mucous membranes.