Transcript Animal Tissues

Animal Tissues
By
Fayez A. Elmabhouh
Department of
Biology
Introduction
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Histology = study of tissues
Tissue = group of cells with similar structure and
function
They are classified according to the shape of the cell,
size, intracellular matrix.
Four types of human tissues:
 Epithelial tissue
 Connective tissue
 Muscular tissue
 Nervous tissue
The organ can may consists of one (heart) or
combination of these tissues (stomach, skeleton, skin)
Four Tissue Types:
1
4
2
3
Epithelial Tissues
Characterized by:
 Their closely connected cells.
 Having very little intracellular substance.
 Resting on a basement membrane.
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Arise from the three germ layers.
No blood vessels enter between its cell but
nerves do
Covers body surfaces and forms glands.
Basement membrane
Embryonic Tissues – all adult tissues are
derived from one of three embryonic
tissues
Ectoderm =
“outside skin”
gut
Mesoderm =
“middle skin”
Animal embryo
Endoderm =
“inside skin”
Cross section
through embryo
Classification of Epithelium
1. Covering epithelia.
2. Glandular epithelia.
Covering epithelia
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The primary function of this type of epithelia
is protection.
Covering epithelia classified according to the
arrangement of the cell into simple epithelia
and stratified epithelia.
Simple epithelia
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These tissues divided into four types
according to the shape of cell and location of
nucleus.
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Consists of a single layer of cells that
are in contact with the basement
membrane.
1. Simple Squamous Epithelium:
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The cells are flat with
smooth edges.
They appear spindleshaped in cross section
Each cell containing a
nucleus in the widest
area.
Found in the lining blood
vessels, covering serosa
Blood vessel
Serosa
Simple Squamous Epithelium
Simple Squamous Epithelium
Bowman’s capsule
2. Simple Cuboidal Epithelium
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The cells in this
epithelium are
square-shaped in
cross section.
Have central and
round nucleus.
Lining the kidney
tubules and Follicles
of thyroid gland
Follicles of thyroid gland
Simple Cuboidal Epithelium
cells
single layer of cube shaped cells; large nuclei
3. Simple Columnar Epithelium
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a.
b.
Built of long pillarshaped cells.
Containing an oval
nucleus.
Ciliated: Bronchioles
Non Ciliated:
lining the ileum
4. Pseudo-stratified Epithelium
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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
free ends.
Lining the trachea.
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Keratinized: the epithelium is covered with
keratin layer which is formed by the dead
squamous cells (horny layer) Skin.
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Non- keratinized: esophagus
Non- keratinized
Keratinized: Skin
1.
2.
Epidermis (Stratified Squamous Epithelium)
Dermis
Transitional- stratified
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Found in the urinary tract (urinary bladder)
Rest on a non clear and non wavy basement
membrane.
Its superficial cells are cuboidal in shape, and
may contain 2 nuclei.
The basal cell layer is formed of high
cuboidal cell.
The intermediate layer are polyhydral cells.
Empty
Full, the cell change into to squamous cell
Glandular Epithelium
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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
Exocrine Glands
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Unicellular: formed of single cell
present in the respiratory tract and
intestinal tract
Multicellular gland
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Made of many cells and each consist of a
secretary portion and duct.
They are either tubular, alveolar in form and
may be simple or compound.
Simple tubular glands
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In the digestive glands, stomach, Large
intestine
Simple alveolar gland
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Form of a flask with a round secretary portion
and a narrow tubular duct.
Mucous and sebaceous gland skin
Compound tubular glands
Compound alveolar gland
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Parotid gland