This presentation include anatomy and physiology of integumentry system of insects ,which will include the process of formation of integumentry system. For further detail go to my u tube channel below : https://www.youtube.com/channel/UC6MjWQizJJ5BQwX2kl34mWg and another channel for similar biology vedios is below: https://www.youtube.com/channel/UCVizmJmI_Asn7x1Ttv_v_QA

1. Anatomy and elementary physiology of
integumentry systems of insects
What do you mean by integumentry systems?
Integumentry systems
The integumentary system is a type of organ system which
comprises the skin and its derivatives. Which has various
functions like to protect the body from various kinds of
damage such as loss of water or damages from outside
environment. The integumentary system generally includes
hair, nails, scales, feathers, hooves etc.

2. Integument
Integument is outer covering or body wall of insects which is
ectodermal in origin. It is rigid, flexible, lighter, stronger and
variously modified in different structures.
Functions of integument or body wall :
● Protection or Mechanical damage
● Absorption
● Excretion and Secretions
● Sensitivity
● Transpiration or geseous exchange
● Aesthetics etc.

3. Structure of integument

5. Basement membrane
● Made up of thin and fibrous layer of
mucopolysachcarides and collegen fibers.
● Digestion and Absorption of cuticle
● Supporting structure for all layers of cuticle
Contain accessory pigment cells in insects
Consists of two layers :
1. Basal lamina - consist Epidermal cells
2. Reticular lamina - contain heamocytes and fat
bodies.

6. Epidermis
● Single cellular layer
● Forms plasma plaques that are site of secretion
for the outer Epicuticle and chitin fibers
● Zonulae adherence - apices and septate junction -
lower side together held epidermis
● Contain E. R., golgi bodies and pigmented cells
also
● Glandular layer of the integument that have
digesting and moulting enzymes for the cuticle
● Cordinariom between the Epidermal cells is

7. ● Epidermal cells contain 3 type of specialised
Glandular cells :
1. Class 1
2. Class 2
3. Class 3
● Class 1 - these are specialised for pheromone
production
● Contact with cuticle through pore canals and
Epicuticular filaments

8. Class 2 cells
● No contact to cuticle
● Have No ducts
● Only known from the sterna glands of
teemites
Class 3 cells
● Contact through ducts
● Forms the End apparatus and secreate cement
on outer surface of cuticle
● Have defensive sections and pheromone
sections

10. Oenocytes
● Derived from the Epidermal cells
● Synthesise Hydrocarbons and lipids that
contribute to the Epicuticle
● Transport Hydrocarbons through heamolymph
and lipids directly through the cytoplasmic
strands
● Hydrocarbons also function as sex hormones in
some species of insects
● These are generally large that is about 100 μm in
diameter

11. Cuticle
It is outermost thick layer of the integument.
It is complex and non cellular.
It forms from the Epidermis or it is a Secretions of
Epidermis. It is rigid or flexible that differ in different
parts of the body.
It is divided into :
1. Epicuticle - upper
2. Procuticle - inner
○ Exocuticle
○ Endocuticle

12. Epicuticle
Multilayer generally 4 layers
Thickness is about 1- 4μm
Generally Chitin is absent in Epicuticle
Different layers of Epicuticle :
1. Inner Epicuticle
2. Outer Epicuticle - non chitinous
3. Wax layer
4. Cement layer

13. 1. Inner Epicuticle
● Tanned layer
● Contains phenol and polyphenols
● Thickest layer
2.outer Epicuticle
● Made up of polymerised lipoprotein
● Thiner layer also called as trilaminar layer
● Nonchitinous layer

14. 3. Wax layer
● Made up of Hydrocarbons
● Contain Oenocytes (Desication)
Transported through pore canals
4. Cement layer
● Secreted by Epidermal layer or dermal
gland
● Made up of lipoprotein
● Protects the body from external damages

16. Endocuticle
● Age determination layer by vertical striations
● It is darkly pigmented
● Hard and sclerotised
● Consists mainly hard protein sclerotin and chitin
Exocuticle
● Present in hot bodies insects
● It is non digested layer
● It is lightly pigmented
● Soft and non sclerotised
● Consists of mainly more chitin

17. Composition of Procuticle
1. Chitin
2. Proteins
3. Lipids
Chitin - polysaccharide of NAG molecule i.e.
N-acetyl glucosamine that are linked through β(1-
4) linkage
● Adjescent chains form microfibrils embeded in
protein matrix and ranges about 2.5 to 3nm
● Ritate in particular direction to form helecoidal
and parallel structures

20. Moulting
It is process of shedding or casting of the old cuticle
and the formation of new one
Processes involved in moulting
● Behavioural changes
● Apolysis
● New Epicuticle formation
● Deposition of Procuticle
● Ecdysis
● Expansion and sclerotisation

21. Behavioural changes
● Stop feeding and become inactive
● Mitotic divisions take place
● Increase tension between Endocuticle and
epidermis
Endocuticle
Epidermis

22. Apolysis
● Separation of the Endocuticle from epidermis
● Suvcuticular or exovial space formation

23. Formation of new Epicuticle
● Forms as patches at the tips of microvilli of
the epidermal cells
● Polyphenols and phenoloxidase are produced to
stabalise the
Forming
Epicuticle

24. Digestion of old Endocuticle
● Digested by enzymes of epidermal cells like
chitinase, proteases and aminopeptidases
● These are generally in inactive form until the new
Epicuticle is formed
● Activated by active transport of k+ions in exovial
space
● Enzymes digest all unscleriotised cuticle except
the ecdysial membrane,Exocuticle, muscle and
nural connection to old cuticle
● Products are reabsorbed generally though the integument

27. Ecdysis
● By increasing blood volume the insects split the
old cuticle that exert pressure from inside
● In preparatory phases it swallows air and water
in Gut to increase the pressure of heamolymph
● Head and thorax comes out first then abdomen
and appentages
● Blood volume is very high so it provides the
hydrostatic skeleton

28. Expansion and sclerotisation
● cross-links between protein molecules to form a
rigid matrix. The process of cross-linking is called
tanning or sclerotisation.
● N-acetyldopamine and N-alanyldopamine are two
compounds known for sclerotisation
● These are oxidised to quinones by phenoloxidases
● Expansion involves swallowing of air and water.
● changes in orientation of chitin microfibrils
● Stretching of the body cuticle thickened the cuticle
layers