Page 492 - Atlas of Histology with Functional Correlations

FIGURE 12.12 ■ Glomus in the dermis of thick skin. Stain: hematoxylin and

eosin. High magnification.

FUNCTIONAL CORRELATIONS 12.3 ■

Arteriovenous Anastomoses and the Glomus

In numerous tissues, direct communications between arteries and veins
called arteriovenous anastomoses bypass the capillaries. Their main

functions are to regulate blood pressure, blood flow, and temperature and
conservation of body heat. A more complex structure for shunts is a glomus
that consists of a highly coiled arteriovenous shunt surrounded by
collagenous connective tissue. The function of the glomus is also to regulate

blood flow and conserve body heat. These structures are found in the
fingertips, external ear, and other peripheral areas that are exposed to
extremely cold temperatures and where arteriovenous shunts are needed.

FIGURE 12.13 | Pacinian Corpuscles in Dermis of

Thick Skin (Transverse and Longitudinal

Sections)

Located deep in the dermis (3) of the thick skin are the Pacinian corpuscles (2,
9). One Pacinian corpuscle is illustrated in a longitudinal section (2) and the
other in transverse section (9).

Each Pacinian corpuscle (2, 9) is ovoid with an elongated central myelinated

axon (2b, 9b) that is surrounded by concentric lamellae (2a, 9a) of compact
collagenous fibers that form the connective tissue capsule (2c, 9c). Between the
connective tissue lamellae (2c, 9c) is a small amount of lymphlike fluid. In a
transverse section, the layers of connective tissue lamellae (9a) surrounding the

central axon (9b) of the Pacinian corpuscle (9) resemble a sliced onion.

In the dermis (3) around the Pacinian corpuscles (2, 9) are adipose cells (5),
blood vessel venule (10), peripheral nerves (4, 6), and cross sections of an
excretory duct (1) and the secretory portion of the sweat gland (8). The

contractile myoepithelial cells (7) surround the secretory portion of the sweat
gland (8).

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