<P> Generally, sweat glands consist of a secretory unit consisting of a base rolled into a glomerulum, and a duct that carries the sweat away . The secretory coil or base, is set deep in the lower dermis and hypodermis, and the entire gland is surrounded by adipose tissue . In both sweat gland types, the secretory coils are surrounded by contractile myoepithelial cells that function to facilitate excretion of secretory product . The secretory activities of the gland cells and the contractions of myoepithelial cells are controlled by both the autonomic nervous system and by the circulating hormones . The distal or apical part of the duct that opens to the skin's surface is known as the acrosyringium . </P> <P> Each sweat gland receives several nerve fibers that branch out into bands of one or more axons and encircle the individual tubules of the secretory coil . Capillaries are also interwoven among sweat tubules . </P> <Table> Differences Between Eccrine & Apocrine Sweat Glands <Tr> <Th> </Th> <Th> Eccrine Glands </Th> <Th> Apocrine Glands </Th> </Tr> <Tr> <Td> Overall diameter of secretory coil </Td> <Td> 500 - 700 μm </Td> <Td> 800 μm </Td> </Tr> <Tr> <Td> Diameter of individual secretory tubule </Td> <Td> 30 - 40 μm </Td> <Td> 80 - 100 μm </Td> </Tr> <Tr> <Td> Composition of secretory unit </Td> <Td> single layer, mixed clear cells & dark cells </Td> <Td> single layer columnar cells </Td> </Tr> <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> </Table> <Tr> <Th> </Th> <Th> Eccrine Glands </Th> <Th> Apocrine Glands </Th> </Tr>

What glands release their product directly into hair follicles