The document details the characteristics and functions of mucus-secreting cells, including the structure of secretory granules and their role in lubrication and barrier formation. It explains the cellular organization, including the presence of intercellular canaliculi, tight junctions, and various organelles such as Golgi complexes and endoplasmic reticulum. The document highlights the differences between serous and mucous cells in terms of their secretory mechanisms and cellular architecture.

1. Serous Mucus
Watery .. rich in protein Mucus or viscos
Type of secretion
Shape of Secretory spherical a tubular
end pieces
number of cell " consist of 8-12 cells surrounding a central lumen
inside the secretory
end "
Shape of cell " inside pyramidal pyramidal
the secretory end "
Location of nuclei with basal spherical nuclei ------------------------
inside cell " LM "
Location of granules granules in the apical cytoplasm -------------
in ' LM'
Secretory granules Electron dense AT apical cytopalsm Electron light
The secretory material appears unstained or stains poorly with
H & E giving an empty appearance to the supranuclear
cytoplasm, but stains strongly by PAS or Alcian blue
STAIN OF --------
SECRETORY
GRANULES
produce mucins, which are glycoproteins but they differ from
most glycoproteins in the structure of the protein core, nature
and the extent of the glycosylation , and in their function
• * Functions of mucins:
1. Lubrication.
2. Form a barrier on the surfaces.
3. Bind and aggregate microorganisms.
1. Proteins.
2. Glycoproteins which have enzymatic &
antimicrobial activity.
PRODUCTION
has fingerlike extensions located between adjacent cells --------------------------------
called intercellular canaliculi
-function : increase the luminal surface
intercellular
canaliculi
-crescent covering the mucous cells (mixed glands.
- secretion reach the lumen through intercellular canaliculi.
Serous demilune -----------------------------

2.  Unlike serous cells, mucous cells lack intercellular canaliculi, except for those covered by demilune cells.
 Function of junctions:
1. Allow passage of certain ions and water between cells and from lumen to intercellular spaces and vice versa.
2. Serve to coordinate the activity of all of the cells within the end piece.
3. Hold the adjacent cells together.
4. Provide information to the cells about their environment.
• The cells contain large amounts of secretory product
(mucus) in the apical cytoplasm, which compresses the
nucleus and ER against the basal cell membrane.
• The mucous (mucigen) granules are swollen, and fuse
with one another. They are electron-lucent.
• In well prepared sections ,the granules appear small,
dense have intact membranes and do not fuse.
- The basal cytoplasm contains numerous
cisternae of rER which converge on a large Golgi
complex located apical and lateral to the nucleus
- The lateral surfaces have occasional folds that
interdigitate with similar processes from the
adjacent cells.
- The basal surface is thrown into regular folds
that extend laterally to interdigitate with those
the adjacent cells.
- The serous cells, as well as mucous cells, also are
joined to one another by:
- 1. Tight junction.
- 2. Adhering junction
- 3. Desmosomes
- 4. Gap junction .
- The cells also attached to the basal lamina and
the underlying C.T. by hemides-mosomes
EM OF CELL
• 1. Large Golgi complex (basal to secretory granules).
• 2. ER and other organelles are limited to the basal
cytoplasm of the cell (basal).
- Cells also contain cytoskeletal components,
mitochondria, lysosomes, and peroxisomes.
-
CONTENT OF CELL IN
EM