Structure of integument in vertebrates shows same basic plane. It comprises two basic layers, that is outer epidermis (ectodermal in origin) and inner dermis (mesodermal origin).

1. Integumentary System in
Vertebrates
STRUCTURE OF SKIN

2. Contents
Comparative Anatomy of Vertebrates, its
meaning and Purpose of Study
What is integument?
Parts of integuments
Histological structure of integument
Structure of epidermis
Structure of dermis
CC-VIII (According to
Undergraduate Model Syllabus
2019 onward)
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3. Comparative Anatomy of Vertebrates, its
meaning and Purpose of Study
1. Comparative anatomy of vertebrates is the comparative study of different body structures in
different groups of vertebrates such as fishes, amphibia, reptilia, aves and mammals.
2. It helpful to determines the phylogenetic origin and modification of various homologous
structures in vertebrates.
3. It gives us an idea about the history of the struggle of animals, striving for compatibility with an
ever changing environment in the past.
4. Despite their differences, all vertebrates, past as well as present, are built according to the same
basic architectural plan. Thus, comparative study of various homologous vertebrate structures
offers special evidence in support of the doctrine of organic evolution with the premise that
species have been changing.
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4. What is integument?
•The term integument is applied to the outermost protective covering of the animal body, the
skin, and its various derivatives.
•Skin also includes the conjunctiva of eyeballs and external surface of eardrums.
•It is directly continuous with the mucous epithelial lining of mouth, rectum, nostrils, eyelids and
urinogenital ducts.
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5. Parts of integuments
The skin of all vertebrates is built according with
the same basic plan.
It is multicellular and differs from that of the
invertebrates in having two layers—
◦ (i) an outer epidermis developed from
ectoderm, and
◦ (ii) an inner dermis derived from the
mesoderm.
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Integument of
Vertebrate
Integument of
Invertebrate

6. Histological structure of integument
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7. Structure of epidermis
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8. Structure of epidermis
The epidermis is a thin, avascular layer that regenerates itself every 4 to 6 weeks.
It’s divided into five layers or strata.
1. Stratum corneum (horny layer): Composed of 10 to 30 layers of polyhedral, anucleated
corneocytes (dead keratinocyte cells), with the palms and soles having the most layers;
flakes and sheds; is easily removed during bathing activities and more efficiently by
scrubbing the surface of the skin; Corneocytes contain a protein envelope (cornified
envelope proteins) underneath the plasma membrane, are filled with water-retaining keratin
proteins, attached together through corneodesmosomes and surrounded in the extracellular
space by stacked layers of lipids; most of the barrier functions of the epidermis localize to
this layer.
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9. Structure of epidermis
2. Stratum lucidum (glassy layer): It lies between the stratum corneum and the stratum
granulosum. This packed translucent line of cells is found only on the palms and soles and not
seen in thin skin.
3. Stratum granulosum (granular layer): Keratinocytes lose their nuclei and their cytoplasm appears
granular. Lipids, contained into those keratinocytes within lamellar bodies, are released into the
extracellular space through exocytosis to form a lipid barrier. Those polar lipids are then
converted into non-polar lipids and arranged parallel to the cell surface.
4. Stratum spinosum (spiny layer): It contains keratinocytes and Langerhans cells. Keratinocytes
become connected through desmosomes and produce lamellar bodies, from within the Golgi,
enriched in polar lipids. Langerhans cells, immunologically active cells, are located in the middle
of this layer.
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10. Structure of epidermis
5. Stratum basale (germinating layer): It consists of single layer of proliferative epidermal cells
(keratinocytes); attached to the basement membrane by hemidesmosomes; contains
melanocytes; melanocytes connected to numerous keratinocytes in this and other strata
through dendrites; can regenerate; Merkel cells are also found in the stratum basale with
large numbers in touch-sensitive sites such as the fingertips and lips. They are closely
associated with cutaneous nerves and seem to be involved in light touch sensation.
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11. Structure of dermis
The epidermis is separated from the dermis, its underlying tissue, by a basement membrane.
The dermis is composed of three major types of cells: fibroblasts, macrophages, and mast cells.
Apart from these cells, the dermis is also composed of matrix components such as collagen
(which provides strength), elastin (which provides elasticity), and extrafibrillar matrix, an
extracellular gel-like substance.
It consists of two distinct layers.
1. Papillary dermis
2. Reticular dermis
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12. Papillary dermis
The papillary dermis is the uppermost layer of the dermis.
It is composed of fine and loosely arranged collagen fibers.
The papillary region is composed of loose areolar
connective tissue.
It is named for its fingerlike projections called papillae or
dermal papillae specifically, that extend toward the
epidermis and contain either terminal networks of blood
capillaries or tactile Meissner's corpuscles.
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13. Reticular dermis
The reticular dermis is the lower layer of the dermis, found under the
papillary dermis.
The reticular region is usually much thicker than the overlying
papillary dermis.
It receives its name from the dense concentration of collagenous,
elastic, and reticular fibers that weave throughout it.
These protein fibers give the dermis its properties of strength,
extensibility, and elasticity.
Within the reticular region are the roots of the hair, sebaceous glands,
sweat glands, receptors, nails, and blood vessels.
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14. Somanath Sahoo
Structure of Integumentary
System in Vertebrates
Guest Lecturer in Zoology
Khallikote Autonomous College,
Berhampur
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