MucusSerousMucus or viscosWatery .. rich in proteinType of secretion

a tubularsphericalShape of Secretory end pieces

consist of 8-12 cells surrounding a central lumennumber of cell " inside the secretory end "

pyramidalpyramidalShape of cell " inside the secretory end "

------------------------with basal spherical nucleiLocation of nuclei inside cell " LM "

-------------granules in the apical cytoplasmLocation of granules in ' LM'

Electron light Electron dense AT apical cytopalsmSecretory granulesThe 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

• 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 .

EM OF CELL

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.