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The hair follicle (C), its sebaceous gland (B), and the arrector pili muscle (A) form the pilosebaceous unit. One or
Education
more sebaceous glands may be associated with each hair follicle. Sebaceous glands secrete an oily substance, se-
bum, into the area surrounding the hair shaft. The glands are located in the connective tissue in the vicinity of the
Holdings,
hair follicle.
The arrector pili muscle is connected to each hair follicle and consists of a bundle of smooth muscle fibers. The
LLC.
muscle extends from the dermal papillae, just under the epidermis of the skin, to insert into the connective sheath of
the hair follicle, and courses around the sebaceous gland. The muscle is controlled by the autonomic nervous system
Not
and its contraction causes the hair to stand on end and the skin to dimple ("goose bumps").
to
be
The more distal portion of the hair follicle is shown in Figure 11-43a. The hair follicle is an invagination of the epi-
redistributed
thelial tissue of the epidermis and consists of several layers of cells. At its termination in the dermis is an expanded
region called the hair bulb. The central area of the bulb contains a core of connective tissue forming a dermal papilla
(arrow). The innermost layers of the hair follicle are keratinized to produce the hair shaft.
or
modified
For a more highly magnified view of the hair follicle and dermal papilla, see Figure 11-43b. Note the continuity of
the connective tissue of the dermal papilla (arrow) with that surrounding the entire hair follicle.
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any
way
without
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