2. GLANDS
Gland is an organ in body that synthesizes substance
for release of substances such as hormones often into
bloodstream(endocrine gland) or into cavities inside
body or its outer surface (exocrine gland)
3. CLASSIFICATION OF GLANDS :
Endocrine glands — are glands that secrete their
products and lack duct system
Exocrine glands — secrete their products through
duct or directly onto apical surface, glands in this
group can be divided into three groups :
9. STRUCTURE OF TERMINAL SECRETORYUNITS
The basic functional unit of a salivary gland is the terminal
secretory unit called ACINI.
Acinar cells of Salivary Glands are classified as :-
SEROUS ACINI MUCOUS ACINI MIXED ACINI
PRODUCE THIN PRODUCE MORE BOTH SEROUS &
WATERY SECRETION VISCOUS MUCUS MUCOUS ACINI;
SECRETION MUCOUS HAVE CAP OF
SEROUS ACINI , KNOWN
AS SEROUS DEMIUNES
10.
11.
12. ACINI
Rest on basement
Arranged in single layer
Intercellular spaces of apical ends of cells separated
from lumen by Junctional complexes
Junctional complexes hold cells together in acini
Regulate permeability
Myoepithelial cells are located on surface of acini
13. Central lumen have a star shaped morphology
It continues via fine series of tubes which constantly
merges with each other and grow larger eventually to
merge into main excretory duct
Mucous acini have larger lumen than serous acini
Intracellular junctions are present in mucous whereas
absent in serous acini
14. SEROUS ACINI Serous acini are protein secreting
cells
Structure
Pyramidal with broad base on
basement membrane
Apex faces lumen
Spherical nucleus placed at basal
region, occasionally binucleated
(Lumen is not usually visible at light
microscope level)
15. Cytoplasm
Apical cytoplasm shows accumulation of secretory granules
Basal cytoplasm is packed with
Parallelly stacked RER, placed basal and laterally to
nucleus
Free Ribosomes
Golgi apparatus
Mitochondria
Lysosomes
16. Secretory granules
Located in apical cytoplasm
Dense core or twisted skin like structure with lighter matrix
Granules are zymogen granules i.e. storage of protein
secreting cells
Mature granules- Dense
Immature granules- Pale
17. MUCOUS ACINI
Mucous acini are mucin secreting
cells
Structure
Tubular configuration
Round profiles surrounding
central lumen of larger size than
serous end pieces
with
Apex of cell appears empty
Have serous associated
them in form of demilunes.
18. forming
Cytoplasm
Thin strands
trabecular network
Appears like thin rim,
compressed against base of cell
Apical cytoplasm has large
amount of secretory products
(mucin)
Mucin compresses nucleus and
ER against cell membrane
19. MYOEPITHELIAL CELLS
Contractile cells associated with secretory end pieces and
intercalated ducts
Stellate shaped with flattened nuclei, scanty cytoplasm, long
branching processes
Intercalated ducts have fusiform shape and elongated processes
These cells lies between basal lamina and joined to each other by
desmosomes
21. DUCTS
Ductal system is varied network of tubules that progressively
increase in diameter
Begins from secretory end pieces to oral cavity
Ducts are for passage of saliva; it actively participates in
production and modification of saliva
23. INTERCALATED DUCTS
Primary saliva produced by secretory end pieces passes first
through it
First cell of duct is adjacent to end pieces, lumen is continuous
with lumen of intercalated duct
Lined by simple cuboidal epithelium, myoepithelial cell bodies
Diameter of duct is smaller than end pieces but their lumen is
larger than end pieces
24.
25. Constitute largest portion of duct system
Located within lobules of duct
STRIATED DUCTS
26. Overall diameter of duct is
greater than secretory end
pieces
Lumen larger than those of
secretory end pieces and
of primary
intercalated ducts
Function
Modification
saliva
secretion Reabsorption and
of electrolytes
27. EXCRETORY DUCTS
Ducts are larger in diameter
than striated ducts
located in connective tissue septa
between lobules of gland
Have psuedostratified epithelium
with columnar cells
Scattered mucous (goblet) cells
may be present
Structure similar to striated
ducts