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INTEGUMENTARY SYSTEM
Presented By
Daw Myint Myint Win
Assistant Lecturer
Department of Zoology
Skin or Integument
[ I ] Structure of skin
As in all vertebrates ,
the skin of rabbit is also built of two main parts or
layers:
( a ) an outer epidermis
( b ) an inner dermis
Below the skin , lymph spaces are absent
Skin is connected with muscles with the help of
specialized connective tissue ( areolar
connective Tissue )
6-6
Cell Types and Layers of the of the Epidermis
Dermal blood vessels
Tactile cell
Melanocyte
Dead keratinocytes
Exfoliating
keratinocytes
Living keratinocytes
Dendritic cell
Stem cell
Dermis
Stratum lucidum
Stratum basale
Stratum granulosum
Stratum spinosum
Stratum corneum
Sweat pore
Tactile nerve fiber
Dermal papilla
Sweat duct
Epidermis
the outer thin stratified epithelium ( epithelial
tissues )
developed from the embryonic ectoderm
does not contain blood vessels ( you can seen
usually rub off dead skin without bleeding )
Keratinocytes of epidermis
The complex epidermis is primarily made of
two zones:
( 1 ) the deeper Malpighian layer and
( 2 ) the superficial cornified layer.
(a) Malpighian layer
The Malpighian layer or stratum Malpighii,
- rests upon the dermis
Malpighian layer is made of living cells
is further subdivided
( I ) Stratum germinativum
( ii ) Stratum spinosum
( iii ) Stratum granulosum
( iv ) Stratum lucidum
1. Stratum germinativum
( intermediate keratin filament )
2. Stratum spinosum ( spiny intercellular bridges )
( beginning of keratohyaline granules )
3. Stratum granulosum
( keratohyaline granules )
4. Stratum lucidum
( a clear intermediate form of keratin )
5. Stratum corneum
( keratin )
cells of corneum epidermis
millions rub off per day .
6-18
Cell Types and Layers of the of the Epidermis
Dermal blood vessels
Tactile cell
Melanocyte
Dead keratinocytes
Exfoliating
keratinocytes
Living keratinocytes
Dendritic cell
Stem cell
Dermis
Stratum lucidum
Stratum basale
Stratum granulosum
Stratum spinosum
Stratum corneum
Sweat pore
Tactile nerve fiber
Dermal papilla
Sweat duct
keratin
Five layers of the Epidermis
( I ) Stratum germinativam or germinal
layer
the innermost layer of the epidermis in contact
with the basement membrane
secreted
by the underlying dermis
- columnar
cells - arranged in a single row one cell think
- continually divide mitotically
- adding new cells to the epidermis
All the glands
( the sweat ,mammary, and sebaceous glands ).
and keratin ( a fibrous proteins ) structures
are derived from this layer
(ii) Stratum spinosum
lies above the germinal layer
also called the transitional layer
several layers thick
Made of polyhedral cells
As these cells are gradually pushed outwards,
they become flattened and keratinized
due to deposition of a horny scleroprotein
known as keratin
(iii) Stratum granulosum
cells in the upper part of stratum spinosum
form the granular layer
containing keratohyaline granules
particularly developed in parts of the body
having thick epidermis such as the palms and the
soles
(iv) Stratum lucidum
Above granular layer in palms and soles only,
a conspicuous, hyaline, non-stainable layer of
shiny and refractile cells
(b) Cornified layer
The outermost cells on the skin surface are
thin, dead and fully keratinized.
form a horny or cornified layer called stratum
corneum
especially thick on soles and palms
The outer portion of this layer is constantly
being worn away, the dandruff is a familiar
example.
New cells are constantly added from below
when the granular cells become horny and die.
This dead layer
tough, prevents mechanical injuries and fungal and
bacterial attacks, and
reduces water loss from the body
The outer surface of epidermis contains minute
openings of sweat glands and hair follicles.
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