Page 527 - Atlas of Histology with Functional Correlations

nucleus and displaces it to the base of the cytoplasm.

In some salivary glands, both mucous and serous cells are in the same

secretory acinus. In these mixed acini, where mucous cells predominate, serous
cells form a crescent, or moon-shaped, cap over the mucous cells. In routine
histologic preparations, these serous crescent-like structures are called serous
demilunes. With new rapid freezing techniques, however, it is believed that

these demilunes may be artifacts of fixation. The secretions from serous cells in
the demilunes enter the lumen of the acinus through tiny intercellular canaliculi
between mucous cells.

Contractile myoepithelial cells are flattened cells that surround both the

serous and mucous acini and the initial portion of the duct system, the
intercalated ducts. They are sometimes called “basket cells” because they
surround the acini with their cytoplasmic branches like a basket. Myoepithelial
cells are located between the cell membrane of the secretory cells in acini and
the surrounding basement membrane.

SALIVARY GLAND DUCTS

Connective tissue fibers subdivide the salivary glands into numerous lobules,
which contain the secretory units and their excretory ducts.

Intercalated Ducts

Serous and mucous, as well as mixed seromucous acini, empty their secretions
into the initial and smallest intercalated ducts with tiny lumina lined with a low
cuboidal epithelium. Contractile myoepithelial cells surround the acini and

portions of intercalated ducts.

Striated Ducts

Several intercalated ducts merge to form the larger striated ducts. These ducts

are lined with a columnar epithelium and, with proper staining, exhibit tiny basal
striations that correspond to the basal infoldings of the cell membrane and the
cellular interdigitations. Located in the basal infoldings are numerous and
elongated mitochondria.

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