Salivary Gland Development

Major salivary glands develop from oral ectoderm at 4-8 weeks of intrauterine life.
Minor salivary glands develop from oral ectoderm after the major salivary glands.
Development stages:
Stage 1: Bud formation (proliferation of oral epithelium into underlying ectomesenchyme)
Stage 2: Cord growth (solid cord of cells forms due to continued proliferation of bud)
Stage 3: Branching in cords (epithelial cord proliferates rapidly and branches into terminal bulbs)
Stage 4: Lobule formation (branching continues at terminal portions of the cord, forming an extensive tree-like system of bulbs)
Stage 5: Canalization of cords (canalization of the epithelial cord, forming a hollow tube or duct)
Stage 6: Cyto-differentiation (mitotic activity shifts to terminal bulb, differentiating into acinar cells, duct cells, and myoepithelial cells)

The ductal system consists of a series of ducts that constantly merge with each other and grow larger, eventually merging into the main excretory duct.
The main excretory duct divides into interlobar and interlobular excretory ducts that enter the lobes and lobules of the gland.
The predominant intralobular ductal component is the striated duct.

The basic functional unit of a salivary gland is the terminal secretory unit called acini.
Acini are made up of epithelial secretory cells, namely serous and mucous cells, and myoepithelial cells.
The cells in the acini are arranged in a single layer and rest on a basement membrane.

Serous acini are typically spherical and consist of 8-12 cells surrounding a central lumen.
The central lumen may have a star-shaped morphology due to the extension of the lumen in between the cells called intercellular canaliculi.

Mucous acini are typically tubular in configuration.
In cross-section, mucous acini appear as round profiles with mucous cells surrounding a central lumen of larger size.
Intercellular canaliculi are absent in mucous acini.

Acinar units consist of serous cells, mucous cells, and myoepithelial cells.
Ductal units consist of intercalated duct, striated duct, and terminal/excretory duct.
Connective tissue components include capsule, septa, and nerves and blood vessels.

Serous cells have a pyramidal shape with a narrow apex near the lumen and a spherical nucleus located in the basal 1/3.
Intercellular canaliculi are present in serous cells.
Serous cells produce proteins and glycoproteins with well-defined enzymatic, antimicrobial, and calcium binding activities.

Mucous cells have a pyramidal shape with a wider apex than serous cells and a flattened nucleus at the base.
Intercellular canaliculi are absent in mucous cells.
Mucous cells produce mucins (glycoproteins) with O-linked oligosaccharide chains.
The main feature of mucous cells is the accumulation of large amounts of secretory product (mucus) in the apical cytoplasm, compressing the nucleus and ER against the basal cell membrane.

Major salivary glands develop from oral ectoderm at 4-8 weeks of intrauterine life.
Minor salivary glands develop from oral ectoderm after the major salivary glands.
Development stages:
Stage 1: Bud formation (proliferation of oral epithelium into underlying ectomesenchyme)
Stage 2: Cord growth (solid cord of cells forms due to continued proliferation of bud)
Stage 3: Branching in cords (epithelial cord proliferates rapidly and branches into terminal bulbs)
Stage 4: Lobule formation (branching continues at terminal portions of the cord, forming an extensive tree-like system of bulbs)
Stage 5: Canalization of cords (canalization of the epithelial cord, forming a hollow tube or duct)
Stage 6: Cyto-differentiation (mitotic activity shifts to terminal bulb, differentiating into acinar cells, duct cells, and myoepithelial cells)

The ductal system consists of a series of ducts that constantly merge with each other and grow larger, eventually merging into the main excretory duct.
The main excretory duct divides into interlobar and interlobular excretory ducts that enter the lobes and lobules of the gland.
The predominant intralobular ductal component is the striated duct.

The basic functional unit of a salivary gland is the terminal secretory unit called acini.
Acini are made up of epithelial secretory cells, namely serous and mucous cells, and myoepithelial cells.
The cells in the acini are arranged in a single layer and rest on a basement membrane.

Serous acini are typically spherical and consist of 8-12 cells surrounding a central lumen.
The central lumen may have a star-shaped morphology due to the extension of the lumen in between the cells called intercellular canaliculi.

Mucous acini are typically tubular in configuration.
In cross-section, mucous acini appear as round profiles with mucous cells surrounding a central lumen of larger size.
Intercellular canaliculi are absent in mucous acini.

Acinar units consist of serous cells, mucous cells, and myoepithelial cells.
Ductal units consist of intercalated duct, striated duct, and terminal/excretory duct.
Connective tissue components include capsule, septa, and nerves and blood vessels.

Serous cells have a pyramidal shape with a narrow apex near the lumen and a spherical nucleus located in the basal 1/3.
Intercellular canaliculi are present in serous cells.
Serous cells produce proteins and glycoproteins with well-defined enzymatic, antimicrobial, and calcium binding activities.

Mucous cells have a pyramidal shape with a wider apex than serous cells and a flattened nucleus at the base.
Intercellular canaliculi are absent in mucous cells.
Mucous cells produce mucins (glycoproteins) with O-linked oligosaccharide chains.
The main feature of mucous cells is the accumulation of large amounts of secretory product (mucus) in the apical cytoplasm, compressing the nucleus and ER against the basal cell membrane.