Comparative anatomy, Integumentary System

1. Quiz
Q1- Discuss about the skin coloration in
amphibian
Q2- Give the functions of the followings
A-Amnion
B-Allantois
C-Chorion

3. Nature and Function of the
Integument
• The outer covering of the body of vertebrates
• Commonly referred to as SKIN
– Includes the mucous membrane lining of the
mouth, eyelids, nostrils and the openings of
rectum and urogenital organs.
– Forms the interface between organisms and the
external environment.

4. Functions of the Skin
1. Keeps water and other substances in a
controlled passage.
2. Protective barrier from mechanical,
chemical, bacterial, UV and thermal
damages
3. Cutaneous receptors: touch, pressure,
temperature & pain
4. Controls body temperature.
5. Synthesizes vitamin D (conversion of
cholesterol Vit D

5. Layers…….
• Skin is composed of
three primary layers:
1. epidermis which
provides
waterproofing and
serves as a barrier to
infection;
2. dermis which
serves as a location
for the appendages
of skin;
3. hypodermis
(subcutaneous
adipose layer), which
is called the

6. Epidermis
•Made up of stratified squamous layer of epithelial cells.
Layers of Epidermis:
1. Stratum corneum- outermost; composed of dead cells;

7. 2. Stratum lucidum- translucent layer, composed of flat
non-nucleated dead cells.
3. Stratum granulosum- composed of keratohyaline
granules
4. Stratum spinosum- composed of Langerhans cells.
5. Stratum germinativum (basale)- inner layer, composed
of actively dividing cells

8. Epidermal cells
• The main type of cells which make up the
epidermis are :
– Keratinocytes- 90% of epidermal cells; produce
keratin.
– Melanocytes- 8 % of epidermal cells; produce
melanin
– Langerhans cells- They specialize in antigen
presentation and belong to the skin immune system
(SIS)
– Merkel cells- make contact with the ending of a
sensory neuron.

9. 2-Dermis
• The dermis lies below the epidermis.
It Provides tensile strength, and
physiologic support for interfacing
epidermis
3-Hypodermis
“Shock absorber”

10. Glandular Epithelium
Types of glands according to
composition:
• Unicellular G.
• Multicellular G.

11. Types of Unicellular gland (basis: shape)
• 1. Club cells
– Elongated, binucleated (amphibians)
– Secretes mucus
– May contain chemicals that stimulates alarm or fear
• 2. Granular cells
– Secretes mucus in skin (lampreys & other fishes)
• 3. Goblet cells
– Narrow apical end, wide base (osteichthyes,
chondricthyes and mammals)
– Secretes mucus

12. Types as to methods of secretion:
1. Merocrine glands- true glands; not destroyed
during secretion; sweatgland
Types of Glands as to Method of
Secretion

13. 2. Apocrine glands- part of the cell is destroyed
that go with the secretion (in the breast of lactating
mammals).
3. Holocrine glands- the entire cell goes with the
secretion but a new cell is produced to replace it;
sebaceous or oil gland

14. Types of Glands as to type of
secretion:
• 1. Mucous glands- secrete mucus
– E.g. simple saccular glands of fishes and
amphibians
2. Serous gland
- secrete watery substance; e.g. sweat glands
3. Sebaceous gland (oil glands)
- Secrete oily substance
- E.g. uropygial glands of birds, ceruminous
glands and Meibomian glands of human

15. Types of Scales
1. Epidermal Scales
-formed from the stratum germinativum
-characteristic of Terrestrial tetrapods
-usually shed and replaced from time to time
-Ex: Scutes of turtles and snakes
2. Dermal Scales
-of mesenchymal origin
-Ex: Fishes’ scales

16. Epidermal scute, Turtle

17. Epidermal scute, Snake

18. – made up of cosmine (dentine-like)
forming thick scales over-layered with thin enamel.
Types of Dermal Scales: Fishes

19. Found in:
Elasmobranchs
Modifications of placoid scales: Shark
teeth; dorsal fin spines

20. Found in :
Gars
Sturgeons
Paddlefish
Redfish

21. Teleost scales
-with comb-like or serrated edges
along the rear margins

22. Bony fish scales
-smooth rear margins

23. - Skin of most fishes is non-keratinized and
covered by a mucus cuticle
Functions of the mucus cuticle in fishes
1. Prevents penetration of bacteria
2. Makes the fish slippery to predators

25. Skin epidermis, Dogfish

26. Fishes Epidermis Dermis
1. Hagfishes and
lampreys
-composed of layers of
numerous epidermal cells
with large granular cells and
elongated club cells
-organized into regular
layers of fibrous connective
tissue containing pigment
cells
2. Osteichthyes
-composed of basal layer of
cells and stratified epidermal
cells above
-secretory and club cells
occur contributing to the
mucous cuticle
-subdivided into a
superficial layer of loose CT
and a deep layer of dense
CT.
3. Chondrichthyes
-numerous secretory cells
and stratified epidermal cells
-presence of chromatophore
on the lower part
-composed of elastic and
collagen fibers giving the
skin strength and prevents
it from wrinkling during
swimming

27. -specialized as a respiratory surface (Cutaneous
respiration)
1. Epidermis
-divided into four layers:
*stratum basale
*stratum spinosum
*stratum granulosum
*stratum corneum

29. -stratum corneum is thin allowing cutaneous
respiration
-capillary beds reach into the lower part for
cutaneous respiration
2. Dermis
-thinner
-composed of fibrous connective tissue divided into
2 layers:
*stratum spongiosum
*stratum compactum

30. -mucous and granular poison glands are
located in the dermis
-chromatophores are located in the dermis but
sometimes found in the epidermis

31. Epidermis
Stratum
spongiosum
Stratum
compactum

32. -more adapted to terrestrial existence than in
Amphibians
-extensive keratinization
-fewer skin glands

33. 1. Epidermis
-divided into three layers:
*stratum basale
*stratum granulosum
*stratum corneum
-epidermal scales are present :
*Scutes -large, plate-like scales
*dorsal part called carapase
Ventral part called plastron

35. -dermal bones located under the epidermal scales are
found in Crocodiles and some Lizards.
2. Dermis
-composed of fibrous connective tissues
Molting or Ecdysis
-shedding of cornified layer of the skin
Stratum basale duplicates the deeper layers of
granulosum and corneum forming new skin

36. THE SHEDDING PROCESS (ECDYSIS)
• When a snake prepares to shed its old skin, a milky liquid
builds up under the outer layer to loosen it from the new layer of
skin formed below.
• This milky film leaves a gray appearance to the snake’s eyes.
• To begin shedding, the snake rubs its head against something
hard to split the skin.
• The snake helps to pull the old skin back by curling around
objects such as logs, branches, and stones. Eventually the
outer skin is left behind.

37. • rattlesnake sheds - 3 to 4 times a year.
•You may find shed skins wrapped around logs, rocks, or near old
building foundations.
•Shed skins may be used to identify the snakes in a surrounding
area.

39. • Molted skin, Boa snake

40. Osteoderms – in alligators

41. Skin glands in Reptiles
-restricted to certain areas of the body
*Femoral glands
-found along the underside of the hindlimbs in the
thigh region of lizards
*Scent glands
-open into the cloaca and on the margins of the
lower jaw in crocodiles and some turtles

42. - Adapted to free movement over the muscles
-Soft except in exposed areas (legs and feet)
-Covered and protected by feathers

43. 1. Epidermis
-composed of statum basale, a transitional layer
and stratum corneum
2. Dermis
-richly supplied with blood vessels, sensory
nerves and smooth muscles
Brood patches
-highly vascularized dermis in the breast
during brooding season

44. Skin glands in Aves:
1. Uropygial glands
-secretes lipid and protein products used in
preening to make the feathers water repellent
2. Salt glands
-excrete excess salt

46. -formed from the beta keratin layer of the epidermis

47. • Long, slender shaft with few
barbs at distal end
• Distributed over the body
surface
• Shaft – embedded in skin
– Peacocks – unusual length

48. Filoplume, Peacock

49. Down feathers
-Smaller and lack the
barbules.
-They are soft and fluffy
-Provide most of the
insulation to the avian body

50. Contour feather or Plumae
• Long shaft: Calamus (hollow quill, embedded in
skin) and Rachis (solid part that bears the vane.
• Vane (broad, flat portion-exposed)
Gives avian body outline or contour
• Flight feathers or contour feather on the wings
• Rectrices – feathers on the tail

52. • Penguin feathers-with minute feathers for
insulation but not for flight or swimming

54. Epidermis
Layers of Epidermis:
1. Stratum corneum-.

55. 2. Stratum lucidum- translucent layer, composed of flat,
dead and non-nucleated cells.
3. Stratum granulosum- composed of keratohyaline
granules
4. Stratum spinosum- cell layer; composed of Langerhans
cells.
5. Stratum germinativum (basale)- inner layer, composed
of actively dividing cells

56. Epidermis of terrestrial
organisms (mammals):
Scent glands can be sebaceous
or sudoriferous
Found in varying locations…
Modification of Mammalian skin
-Hooves
-beak
- Plate (shields)
-Antler
-Horn
-Eyebrows
-Glands
-Short Knobbed horn
-Baleen Plate

57. The Epidermis
Claws, hoofs and nails:
Claws, nails and hooves
homologous
Similar structure…
*Unguis
*Subunguis
*Cuneus (frog)
http://www.science-art.com/gallery/170/170_8212006165155.jpg
http://anatomy.iupui.edu/courses/histo_D502/D502f04/lecture.f04/integument.f04/nail.jpg

58. – Unguis: The nails are part of the outer layer of the skin
and are composed of hard tissue formed of keratin. Called
also unguis. Parts of the nail.
-Subunguis
is the soft, flaky layer, located in the ventral parts of nail or
claw.
– Cuneus (frog)
force into a narrow spac

59. The Epidermis
Hair:
Functions of hair…
•Thermoregulatory)
•Sensory (vibrissae)
•Protective
http://www.brownlog.dreamhost.com/scrapbook/1998_09_tacoma/zoo_walrus.jpg

60. The Epidermis
Horns:
*Bovine horns
*Hair horns (Rhino horn)
*Antlers of giraffe horns
http://www.skullsunlimited.com/graphics/pronghorn_skull.jpg
http://www.oucom.ohiou.edu/dbms-witmer/images/Rhino_horn_UV_large.jpg
http://animaldiversity.ummz.umich.edu/site/resources/phil_myers/horns_antlers/giraffe.jpg/thumbnail.jpg

61. Epidermis - beaver tail

62. • Types of epidermal gland are -----------
- mucous glands
- poison glands
- femoral glands
- uropygial gland
- sweat glands,
- sebaceous gland
- wax gland
- meibomian gland,
- scent gland (are found in the genital area of most mammals)
- mammary glands
- all are exocrine gland

63. Musk Glands
• Scent glands
• Along carapace in turtles
• Under lower jaw in crocodiles
• Musk deer
– Take secretions to make perfume

64. Musk deer

66. grey amber, is a solid, waxy, flammable substance of a dull grey or
blackish colour, produced in the digestive system of sperm whales.
The word "amber" is derived from the Arabic word for ambergris, ‫عنبر‬
Ambergris
•used in perfume manufacture.