Also known as exocrine glands, the eccrine and apocrine glands are two types of sweat glands. They secrete their substances directly out to the surface of the body instead of into the bloodstream. Although they are both coiled, tubular glands, there are several differences between the two. The apocrine glands are slightly larger and produce a thicker and more odorous sweat. The eccrine glands are located over almost the entire body, while the apocrine glands are located mainly in the armpits, genital area, and around the nipples.

The sweat produced by the apocrine glands contains proteins, fats, and other substances that result in a thicker and stickier sweat. In addition, the sweat is broken down by the bacteria on the surface of the skin, often causing an unpleasant odor to arise. Even though the glands are present at birth, they do not begin to function until puberty, which is why young children do not need to wear deodorant.

The apocrine glands reach deep into the layer of the dermis and secrete their fluids into the tiny canals of the hair follicles. The eccrine glands, however, do not reach as far into the dermis and secrete their fluids directly onto the skin's surface via the pores. Another key difference between the eccrine and apocrine glands is the size of the lumen, also known as the opening, which is slightly larger in the apocrine glands.

Although located in just about all areas of the skin's surface, the eccrine glands have a higher density in the palms, soles of the feet, and scalp areas. The sweat is usually odorless and contains high amounts of sodium and other electrolytes. Therefore, it is important to consume plenty of electrolyte fluids when the body produces a lot of sweat.

The purpose of the eccrine glands is to help control the temperature of the body. As the body temperature increases, the sweat secretion increases as well, allowing the temperature to drop. Exercise, stress, and excitement can also activate these glands. Another benefit of the sweat produced by the eccrine glands is that it helps to protect the body against harmful bacteria and other viruses.

There is no scientific evidence regarding the purpose of the apocrine glands. In animals, they seem to act as scent glands that aid in attracting the opposite sex, which some state holds true for humans as well. In addition, they are also said to have an effect on hormones and can potentially interfere with the menstrual timing in women. These glands are primarily activated by stress or excitement.