striated DuctsIntercalated Ducts

intercalated ductsecretory end piecesReceive the 1 ry saliva from

columnar with a centrally placed nucleus and pale, acidophilic cytoplasm.

Lined by a simple cuboidal epithelium , central nucleus and myoepithelial cells.

Centrally placed nuclei. . Small rER. . Small Golgi complex. Few small secretory granules in the apical cytoplasm. The apical surface has a few short microvilli projecting

into the lumen

The duct cells

Tight junctions. 2. Junctional complex.

(but lack of gap junctions).

1. Apical junctional complex.2. Scattered desmosomes.3. Gap junctions .4. Folded processes of adjacent cells.

lateral surfaces are joined by

• contains:1. Small secretory granules (filled with proteins).2. Vesicles (endocytosis from lumen).3. Numerous lysosomes.4. Peroxisomes (get rid of toxic substances like hydrogen peroxide, or other metabolites) 5. Gylcogen deposits (in perinuclear cytoplasm).

Few small secretory granulesThe apical cytoplasm

• Largest portion of the duct system.• Located within the lobules (intralobular).

• Undifferentiated c ells (stem cell) in the intercalated ducts may proliferate and undergo differentiation to replace

charactristic

• The lumen is larger than those of secretory cells and intercalated ducts.

• Surrounded by a basal lamina The duct cells show basal striations result from numerous RADIALLY arranged mitochondria (why) in narrow cytoplasmic partitions, separated by highly infolded basolateral membrane (EM).

•

damaged or dying cells in the end pieces and striated ducts.

• Because of their small size, the duct are difficult to identify in routin histologic sections.

• Modification of 1ry saliva by reabsorption and secretion of electrolytes (Ca2+, Cl-, Na+, HCO- , K+).

replace damaged or dying cells in the end pieces and striated ducts.

function