<Tr> <Td> Composition of ductal epithelium </Td> <Td> two or more layers of cuboidal cells </Td> <Td> double layer of cuboidal cells </Td> </Tr> <Tr> <Td> Duct opens to </Td> <Td> skin surface </Td> <Td> hair follicle, sometimes nearby skin surface </Td> </Tr> <P> The number of active sweat glands varies greatly among different people, though comparisons between different areas (ex . axillae vs. groin) show the same directional changes (certain areas always have more active sweat glands while others always have fewer). According to Henry Gray's estimates, the palm has around 370 sweat glands per cm; the back of the hand has 200 per cm; the forehead has 175 per cm; the breast, abdomen, and forearm have 155 per cm; and the back and legs have 60--80 per cm . </P> <P> In the finger pads, sweat glands are somewhat irregularly spaced on the epidermal ridges . There are no pores between the ridges, though sweat tends to spill into them . The thick epidermis of the palms and soles causes the sweat glands to become spirally coiled . </P>

Where are the sweat glands located on the head