Pseudostratified columnar one layer single layer of

Pseudostratified
columnar
One layer Single layer of cells of differing
heights , some not reaching the
free surface; nuclei seen at
different levels; may contain
mucus-secreting goblet cells and
bear cilia.
Secretion, particularly of
mucus; propulsion of
mucus by ciliary action.
 Non-ciliated type in
male’s sperm-carrying
ducts and ducts of large
glands;
 Ciliated variety lines the
trachea, most of the
upper respiratory tract.
Stratified squamous Several
layers
Thick membrane; basal cells are
cuboidal or columnar and
metabolically active; surface
cells are flattened (squamous) ;
in the keratinized type, the
surface cells are full of keratin
and dead; basal cells are active
in mitosis and produce the cells
of the more superficial layers.
Protects underlying tissues
in areas subjected to
abrasion.
Nonkeratinized type forms the
moist linings of the
esophagus, mouth, and
vagina; keratinized variety
forms the
epidermis of the skin, a dry
membrane.

Stratified cuboidal Generally,
two layers of
cube-like
cells.
Cube-like cells . Protection. Largest ducts of sweat glands,
mammary glands, and salivary
glands.
Stratified columnar Several
layers
Several cell layers; basal cells
usually cuboidal ; superficial cells
elongated and columnar .
Protection; secretion. Rare in the body; small
amounts in male urethra and
in large ducts of some glands.
Transitional About 6
layers
Resembles both stratified
squamous and stratified
cuboidal ; basal cells cuboidal or
columnar ; surface cells dome
shaped or squamous-like ,
depending on
degree of organ stretch.
Stretches readily and
permits distension of
urinary organ by contained
urine.
Lines the ureters, bladder, and
part of the urethra.
Why are cuboidal or columnar cells found
in epithelia that function in secretion and
absorption? List three
locations of cuboidal epithelium.
Why is columnar epithelium not found in
locations where diffusion occurs? What type of
epithelium isfound in these locations?
Epithelial Cell Features
Epithelial Cell Feature Structure Function Apical side, Basal side,
or Lateral side of the
cells
Tight junction: In the apical
region of most epithelial
tissues; belt-like tight junction
(or a zonula occludens);
extends around the periphery
of each cell
 Adjacent cells are so close that
some proteins in their plasma
membrane are fused. This forms a
seal that closes off the
extracellular space
 Some tight junctions are more
leaky than others and may let
certain types of ions through.