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152 ANATOMY

are found at various depths in the subcutaneous connective tissue, sur-
rounded by adipose tissue.
They are tubular, with a coiled, rounded, or flattened extremity, the
duct through the epiderm resembling a spiral screw. This duct ascends
vertically through the true skin and cuticle, terminating in an enlarged
pore or aperture (Fig. 76). Occasionally these glands are formed of two
tubes coiled around each other. When so formed the tubes unite at the
superior extremity of the gland and form one duct.
Both the duct and the gland proper are invested with connective
tissue similar to and continuous with the corium. Situated within this
tissue, which forms the outer
Fig. 7
portion of the tube, is a
thin membrane which tra-
verses the gland and the
duct as far as the epidermis,
and is analogous to, and
continuous with, the base-
ment-membrane of the skin.
That portion of the tube
above this basement-mem-
brane is epidermic in struc-
ture, while the coiled por-
tion, or the true secreting
gland, is lined by a single
layer of cuboidal and poly-
hedral epithelium (Fig. 77),
with nuclei, and often con-
taining pigment - granules.
Between these cells of the
basement - membrane is a
Section of Coil of a Sweat-^land : S\ tuhule lined by layer of non-striated mus-
cuboidal epithelia; T, central calibre of the tuhule; D,
the beginning of the duct; C, connective tissue wiih cular fibres arrano-ed lone-i-
Injected blood-vessels (magnifieid 500 diameters).
tudinally. These fibres are
not found in the duct, which coils several times before leavino^ the
gland.
The duct proper is lined by an extremely fine cuticular membrane.
Between this lining and the basement-membrane are situated two or
three layers of epithelial cells. The epithelium within the tube forming
both the gland and the duct is continuous with the epidermis.
The Cerumlnous Glands found within the external auditory meatus
are so similar to the sudoriferous glands in structure and mode of
development that they have been classed as of that varietv.
Sweat-glands are tJurrounded by numerous blood-vessels.
The Sebaceous Glands belong to the racemose variety. They are dis-
tributed over almost the entire surfiice of the body, with the exception
of the palms of the hands, soles of the feet, and the backs of the last
])halanges of the fingers and toes. They are situated within the corium
of the skin, and are usually connected with the hair-follicle by two
ducts which empty into it a little below its mouth. These glands do
not pass into the subcutaneous tissue.