Histology = study of tissues
Tissue = group of cells with similar structure and
They are classified according to the shape of the cell,
size, intracellular matrix.
Four types of human tissues:
The organ can may consists of one (heart) or
combination of these tissues (stomach, skeleton, skin)
Their closely connected cells.
Having very little intracellular substance.
Resting on a basement membrane.
Arise from the three germ layers.
No blood vessels enter between its cell but
Covers body surfaces and forms glands.
Embryonic Tissues – all adult tissues are
derived from one of three embryonic
The primary function of this type of epithelia
Covering epithelia classified according to the
arrangement of the cell into simple epithelia
and stratified epithelia.
These tissues divided into four types
according to the shape of cell and location of
Consists of a single layer of cells that
are in contact with the basement
1. Simple Squamous Epithelium:
The cells are flat with
They appear spindle-
shaped in cross section
Each cell containing a
nucleus in the widest
Found in the lining blood
vessels, covering serosa
3. Simple Columnar Epithelium
Built of long pillar-
Containing an oval
a. Ciliated: Bronchioles
b. Non Ciliated:
lining the ileum
4. Pseudo-stratified Epithelium
Single layer of cells which rest on a
basement membrane but do not all reach to
the free surface of the epithelium.
Their nuclei found at different levels giving
the a false stratified appearance.
Cells that reach the surface carry cilia at their
Lining the trachea.
Keratinized: the epithelium is covered with
keratin layer which is formed by the dead
squamous cells (horny layer) Skin.
Non- keratinized: esophagus
Found in the urinary tract (urinary bladder)
Rest on a non clear and non wavy basement
Its superficial cells are cuboidal in shape, and
may contain 2 nuclei.
The basal cell layer is formed of high
The intermediate layer are polyhydral cells.
Full, the cell change into to squamous cell
The cells are specialized in secretion and
thus form glands.
Formed from collections of Epithelial cell
Glands with ducts are termed exocrine
Glands without ducts are termed endocrine