Connective tissue: Epithelial
tissues
, Introduction
Composed of closely aggregated polyhedral cells
with very little extracellular substance.
These cells have strong adhesion due to adhesion
molecules, membrane interdigitations, and
intercellular junctions. These features allow the
cells to form cellular sheets that cover the surface
of the body and line its cavities or are arranged as
three-dimensional secretory units.
, Introduction
The principal functions of epithelial tissues are:
• covering and lining of surfaces (eg, skin, intestines),
• absorption (eg, intestines)
• secretion (eg, glands)
• sensation (eg, gustative and olfactory neuroepithelium),
and
• contractility (eg, myoepithelial cells).
Because epithelial cells line all external and internal
surfaces of the body, everything that enters or leaves the
body must cross an epithelial sheet.
, The Forms & Characteristics of Epithelial Cells
• The forms and dimensions of epithelial cells
range from high columnar to cuboidal to low
squamous cells.
• Their polyhedral form is the result of their
juxtaposition in layers or three-dimensional
assemblages.
• Epithelial cell nuclei have distinctive shapes,
varying from spherical to elongated or elliptic.
tissues
, Introduction
Composed of closely aggregated polyhedral cells
with very little extracellular substance.
These cells have strong adhesion due to adhesion
molecules, membrane interdigitations, and
intercellular junctions. These features allow the
cells to form cellular sheets that cover the surface
of the body and line its cavities or are arranged as
three-dimensional secretory units.
, Introduction
The principal functions of epithelial tissues are:
• covering and lining of surfaces (eg, skin, intestines),
• absorption (eg, intestines)
• secretion (eg, glands)
• sensation (eg, gustative and olfactory neuroepithelium),
and
• contractility (eg, myoepithelial cells).
Because epithelial cells line all external and internal
surfaces of the body, everything that enters or leaves the
body must cross an epithelial sheet.
, The Forms & Characteristics of Epithelial Cells
• The forms and dimensions of epithelial cells
range from high columnar to cuboidal to low
squamous cells.
• Their polyhedral form is the result of their
juxtaposition in layers or three-dimensional
assemblages.
• Epithelial cell nuclei have distinctive shapes,
varying from spherical to elongated or elliptic.
