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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