TYPES OF SIMPLE EPITHELIUM
SQUAMOUS-: Cells are flat, height of the cell is very little as
compared to the width.
CUBOIDAL-: Cells are cube shape, height and width of the cell
are more or less equal.
COLUMNAR-: Cells are rectangle shape, height is distinctly
greater than the width.
TYPES OF STRATIFIED EPITHELIUM
1i)Stratified squamous-: Multilayer, cell towards deeper layer are
columnar but proceeding towards surface of the epithelium the
cells become increasingly flattened(squamous)
1ii)Stratified cuboidal-: Made up of 2 or more layer of cuboidal
1iii) Stratified columnar-: Made up of 2 or more layer of
2) Transitional epithelium( Urothelium )-:
Multilayered,cuboidal,polygonal or rounded ,umbrella shape
cell,Confined to the urinary tract.
Pseudo stratified columnar epithelium-: Really single layer of
columnar epithelial cell but give false appearance of
Cytoplasm of cells in this kind of epithelium forms only a thin
Nuclei produce bulging of the cell surface.
Cells shows polygonal outline(Surface view) interlock with those
of adjoining cells.
EM-:Marked occluding junction between cells. Tightly sealed.
Example-: Alveoli of lungs, Free surface of serous pericardium ,
free surface of pleura, free surface of peritoneum called
mesothelium , lines the inside of the heart called endocardium ,
lines the inside of blood vessels and lymphatic's called
endothelium, lines some part of renal tubule and some part of
In vertical section the cells of this epithelium are rectangular and
On surface view cells look polygonal.
Frequently elongated nuclei present and lie in a row towards the
base of the cell.
Surface view or transverse section shows polygonal shape.
Classified according to the nature of the free surface of the cell.
b) Stratified columnar c)Ciliated columnar with striated border
and brush border.
STRIATED COLUMNAR EPITHELIUM
Surface is covered with microvilli visible with EM with the light
microscope the region of the microvilli is seen as striated
border.(Microvilli’s are arranged regularly)
Microvilli’s are placed irregularly.
Secretion by apical part of cytoplasm contain secretory
Example-: Present over mucous membrane of stomach and the
large intestine.(Simple columnar without cilia or microvilli).
Example-: Columnar epithelium with striated border(Small
Example-: Columnar epithelium with brush border(Gall bladder).
CILIATED COLUMNAR EPITHELIUM
Function-: Expulsion of the foreign body.
Example-: Most of the respiratory tract, uterus, uterine tubes,
efferent ductules of the testis , part of the middle ear, auditory
tube, ependyma lining the central canal of the spinal cord,
ventricles of the brain.
Move mucous accumulating in the bronchi.
Trapped dust particle towards larynx and pharynx.
When excessive this mucous is brought out as sputum during
Passage of ova towards uterus.(Uterine tube).
They are secretory columnar cell scattered in the mucosa of
stomach and intestines.
Present in apical part of cell.
Acquire a characteristic shape.
Some columnar cell secrete enzyme.
Similar to columnar epithelium.
Height of the cell is about the same as their width.
Nuclei are usually rounded.
Example-: Follicle of the thyroid gland, ducts of many gland,
surface of the ovary called germinal epithelium, choroid plexus,
inner surface of the lens, pigment cell layer of the retina.
Lines the secretory elements of many glands
Cuboidal epithelium with prominent brush border is seen in
proximal convoluted tubules of the kidneys.
PSEUDO STRATIFIED COLUMNAR EPITHELIUM
Nuclei appear to arrange in two or more layer.
Epithelium is more than one cell thick.
Actually one layer of cell.
But some cells are broader near the base and other near the
Nuclei lie in the broader part of each cell and are therefore not
in one layer.
Not true stratified.
STRATIFIED SQUAMOUS EPITHELIUM
Made up of several layers of cells.
Cell of the deepest or basal layer rest on the basement
membrane. They are usually columnar in shape.
Lying over the columnar cells they are poly hedral or cuboidal
As they pass towards the surface of the epithelium these cells
become progressively flat.
Types-:a) Non keratinized b) Keratinized
Surface epithelium remains moist.
Most superficial cells are living
Nuclei can be seen in them.
Example-: Found over the body surface that subject to friction.
Seen in, mouth,tongue,pharynx,oesophagus,vagina,cornea
Contrast to non keratinized epithelium.
Epithelial surface is dry.
Most superficial cells die.
Nuclei is lossed.
The cells contain a substance called keratin.
Example-: Skin surface of the whole body.
Shows frequent mitosis.
Multi layered.4 to 6 cell thick . Cell at the surface are not
Differs from stratified squamous epithelium.
Deepest are columnar or cuboidal.
Middle layers are made up of poly hedral or pear shaped cell.
Cell of the surface layer are large and often shape like umbrella.
Example-: Renal pelvis and calyces, ureter, urinary bladder.
Nature-:Stretchable.( cells become flattened and rounded)
Definition-: The tissue which fills the interstices between more
specialized elements; and serves to hold them together and
support them. It is otherwise called support tissue.
Example-: Superficial fascia.(When an area of skin is lifted off
from underlying tissues (during dissection) the two are seen to
be connected by a delicate network of fibres. It provides support
to the delicate epithelial tissue.
In the section across a salivary gland some epithelium lined
acini and one duct are seen. Filling the interstices between
these elements there is connective tissue.
In oesophagus an epithelial lined mucosa separated by an
short distance from thick layer of muscle. The interval between
the two is filled by connective tissue. Over all these are called
general connective tissue.
BASIC COMPONENTS OF GENERAL CONNECTIVE TISSUE
1)Ground Substance-:Many tissues and organs of the body are
made up mainly of aggregations of closely packed cells. e.g. epithelia
and solid organs like liver. In contrast cells are relatively few in
connective tissue. And are widely separated by a prominent
intercellular substance. The intercellular substance is in form of
ground substance. Within which there are numerous fibres.
2) Fibres ( embedded in amorphous ground substances or
a) Collagen fibres
b) Reticular fibres
c) Elastic fibres
3) Cells-: a) Cells that are intrinsic component .( fibroblast,
undifferentiated mesenchymal cell, pigment cells, fat cells)
b) Cells belongs to immune system(Macrophage or histiocytes, mast
cell, lymphocytes, plasma cells, monocytes, eosinophils)
DIFFERENT FORM OF CONNECTIVE TISSUE
Loose connective tissue-: When we
examine a small quantity of superficial
fascia under a microscope at low
magnification it is seen to be made up
mainly of bundles of loosely arranged
fibres that appear to enclose large
space. This is loose connective tissue.
Spaces are also called areola, and
such tissue is also referred to as
In this fibre bundles are much more conspicuous and form a
dense mass. This kind of tissue is referred to as fibrous tissue. It
appears white in colour and is sometimes called white fibrous
REGULAR FIBROUS TISSUE
In some situation
the bundle of
collagen fibres are
to one another in
a very orderly
manner. This kind
of tissue is called
tissue or regular
EXAMPLE OF REGULAR FIBROUS TISSUE
Ligaments Sheets of
The bulk of connective tissue is
formed by elastic fibres; this is
called connective tissue.
Yellow in colour.
Example: Ligamentum nuchae.(
Back of the neck.
Ligamentum flava( Connect
lamina of adjoining vertebra).
The vocal ligament of the larynx.
Deep layer of superficial fascia
covering the anterior abdominal
Fuse with each other to form
sheet usually fenestrated. Such
sheet support wall of large
They form internal elastic lamina
in smaller arteries.
Made up of reticular fibres.
In many situations(e.g.
lymph nodes, glands)
these fibres form
supporting networks for
In some situations(bone
nodes) the reticular
network is closely
associated with reticular
cells. Many of these cells
are fibroblasts, but some
may be macrophages.
FIBRES OF CONNECTIVE TISSUE
COLLAGEN FIBRES-: Seen in
bundles, straight or wavy. The
bundle are made up of collection
of individual collagen fibres.
Bundle branch or anastomose
with adjacent bundle but
individual fibre do not branch.EM
shows fibrils 20-200nm
Types I-: Connective
TypeII-: 20-100nm diameter,
Striations are less prominent,
form fibrous basis of hyaline
cartilage, present in vitreous
TypeIII-: Form reticular fibres.
TypeIV-: Short filament that form
sheet, basal lamina of basement
membrane, lens capsule.
These are a variety of collagen
uneven in thickness, they form
network or reticulum by
branching and by anastomosing
with each other. They do not run
in bundles, easily stained by
silver impregnation, which
renders them black, easily
distinguish from type 1 collagen
fibres which are stain brown,
because of their affinity to silver
salt are called argentophil fibres,
contain more carbohydrates,
provide supporting network,Ex.
ial component of all basement
membrane, smooth muscle,
In areolar tissue fibres are much
They run singly not in bundles.
Branch and anastomose with
Thinner than collagen
Periodic striation not present.
In some situation they are thick
E.g. Ligamenta flava.
Wall of large arteries they form
EM view shows central
amorphous core and a outer
layer of fibrils made up of
glycoprotein's called fibrillin.
CELLS OF CONNECTIVE TISSUE
3) Cells-: a) Cells that are intrinsic component .( fibroblast,
undifferentiated mesenchymal cell, pigment cells, fat cells)
b) Cells belongs to immune system(Macrophage or histiocytes,
mast cell, lymphocytes, plasma cells, monocytes, eosinophils)
FIBROBLAST(CELLS OF INTRINSIC COMPONENT)
These are most numerous in
cells of connective tissue
It concerned with the
production and lay down of
They are fixed cell in tissue
section these cell appear
spindle shape, flat nucleus,
surface view shows
Nucleus is large euchromatic
and has prominent nucleoli.
The amount of cytoplasm
and of organelle varies
depending upon activity. In
inactive fibroblast the
cytoplasm becomes scanty
and the nucleus is
heterochromatic. Often called
UNDIFFERENTIATED MESENCHYMAL CELL
It is called embryonic
connective tissue is called
It is made up of small cells
with slender branching
That joins to form a fine
Easily distinguished as
they contain brown
pigment called melanin in
Most abundant in
connective tissue of the
skin, choroid and iris of the
It varies in different races
and different individuals.
Contain pigment in their
called melanocytes are of
neural crest origin.
Are called adipocytes.
Some amount of fat may
be present in cytoplasm.
Also called lipocytes.
Some cell stores fat in
large amount and become
distended with it.
Aggregation of fat cell
constitute adipose tissue.
MACROPHAGE(CELLS OF IMMUNE SYSTEM)
Large series of cell
present in the body.
Macrophage cells of
connective tissue are also
called histiocytes or
They have the ability to eat
up or phagocytose
unwanted cells includes
Such material is usually
Small, rounded, oval cell
also called mastocytes or
Nucleus is small centrally
placed irregular microvilli
or filipodia are present on
the cell surface.
Distinguish feature is
numerous granules are
present in cytoplasm
demonstrated with PAS
Represents a variety of leucocytes white
blood cell present in blood.
Large aggregation of lymphocytes are
present in lymphoid tissue.
They reach connective tissue from these
sources and are especially numerous
when the tissue undergoes
Play an important role in defence of the
body against invasion by bacteria and
They have the ability to recognize
substances that are foreign to the host
And to destroy these invaders by
producing antibodies against them.
Types-: B-Lymphocytes –Pass through
blood to reach other tissue and mature
into plasma cells.
T-Lymphocytes travel through blood
from bone marrow to thymus.
EOSINOPHILS AND PLASMA CELLS
because of presence of
eosinophilic granules in the
Increase in number in allergic
Increase in number in certain
types of inflammation.
Small rounded chromatin in its
nucleus form 4 to 5 clumps near
the periphery of the nucleus.
Thus giving the nucleus a
resemblance to a cart wheel.
Cytoplasm is basophilic.
Produce antibodies that may be
discharge locally may enter the
circulation or may be stored
within the cell itself in the form
of inclusions called Russell's
Basically an aggregation of fat cells. Also
called adipocytes. Each fat cell contains a
large droplet of fat that almost fills it. As
result cell becomes rounded. When
several fat cells are closely packed they
become polygonal because of mutual
Cytoplasm is thin just deep to plasma
membrane. The nucleus is pushed against
the plasma membrane and is flattened.
Distribution-: Superficial fascia.
Subcutaneous layer of fat is called
Gives smooth contour to the skin.
Fills several hollow spaces in the body.
These include orbit axillae and the
Present in bone marrow.
Present in many abdominal organs around
it. E.g. Kidney-: Perinephric fat.
Considerably stored in greater omentum
and in other peritoneal folds.
Function-: 1) Acts as store house of
Regarded as insulator against heat loss.
FUNCTIONS OF CONNECTIVE TISSUE
Acts as a packing material.
Provides supporting matrix for
many highly organised structures.
Forms restraining mechanism of
the body in the form of retinacula,
cheque ligament and fibrous
Preserves the characteristic
contour of the limbs.(deep fascia)
Aid circulation in the vein’s and
Provides surface coating of the
body in the form of superficial
fascia. Stores fat and conserves
Connective tissue develops from
embryonic mesenchyme. These
are capable of transformation into
each type of connective tissue.
Provides additional surface for the
attachment of muscles in the form of
deep fascia, intermuscular septa and
Forms fascial planes which provide
convenient pathway for blood
vessels,lymphatics and nerves.
Facilitates movements between
adjacent structures and by forming
bursal sacs it minimizes friction and
Helps in repair of injuries where by the
fibroblast lay down collagen fibres to
form the scar tissue.
Macrophage serves a defensive function
against the bacterial invasion.
Plasma cells are capable of producing
Pigment cell protect the skin against
ultra violate rays.
ELEMENTS OF CONNECTIVE TISSUE
B) Reticulin fibres.
C) Collagen fibres.
Non fibrous elements.
A) Ground substances.
Definition-: Is the general
covering of the entire
external surface of the body
including the external
auditory meatus and the
outer surface of the tympanic
It is continuous with the
mucous membrane at the
orifices of the body.
Colour of the skin is
determined by at least five
pigments present at different
A) Melanin-: Brown in colour
present in the germinative
zone of the epidermis.
melanin ,present diffusely
through out the epidermis.
C) Carotene, yellow to orange
in colour present in stratum
E) Oxyhaemoglobin,present in
the cutaneous vessels.
Composed of 2 distinct layers,
epidermis and dermis.
Epidermis-: a) Superficial b)
Avascular c) Stratified squamous
epithelium d) Origin ectodermal
e) Give rise mainly to
appendages of the skin
namely hair,nails,sweat glands
and sebaceous glands.
Structurally made up of a
zone(stratum corneum and
stratum luciderm) and deep
Deep vascular layer of the
Derived from mesoderm.
Arranged into superficial
papillary layer, a deep reticular
Superficial papillary layer
forms conical , blunt
papillae)which fit into
reciprocal depressions on the
under surface of the
Deep reticular layer is
composed chiefly of the white
fibrous tissue arranged mostly
in parallel bundles.
The skin is marked by 3 types
of surface irregularities.
A) Tension lines-: Form a
network of linear furrows
which divide the surface into
polygonal or lozenge shape
B) Flexure lines-: Are certain
permanent lines along which
the skin folds during habitual
movements chiefly flexion of
C) Papillary ridges-: Are
confined to palms and soles
and their digits. They form
narrow ridges separated by
fine parallel grooves.
APPENDAGES OF SKIN
Definition-: Nails are hardened
keratin plates( cornified zone) on
the dorsal surface of the tip of the
fingers and toes ,acting as a rigid
support for the digital pads of
Parts-:Root-: Proximal hidden
Free border-: Is the distal part
free from the skin.
Body-: Is the exposed part of the
nail which is adherent to the
Lunule-: Proximal part of the
body presents a white opaque
Each lateral border of the nail
body is overlapped by a fold of a
skin,termed the nail wall.
PARTS OF NAIL
The skin( germinative zone
+corium) beneath the root
and body of the nail is called
nail bed. The germinative
zone of the nail bed beneath
the root and lunule is thick
and proliferative (germinal
matrix) and is responsible
for the growth of the nail.
The rest of the nail bed is
thin ( sterile matrix) over
which the growing nail
Corium is very vascular.
This accounts for their pink
CLINICAL ANATOMY OF THE NAIL
Anaemia(Nails are pale and white)
Koilonychias-: In iron deficiency anaemia nails are thin, brittle
and spoon shaped.
Clubbing-: Hypertrophy of the nail bed cause in suppurative
disease like lung abscess, bronchiectasis,osteomylitis ,severe
type of cyanosis (Fallot’s tetrology, chronic congestive cardiac
Disturbance of the nail growth due to acute illness or trauma
give rise to transverse grooves in the nail substances.
Hair are keratinous
filaments derived from
invaginations of the
germinative layer of
epidermis into the dermis.
Help in conservation of
Distributed all over the
body except for the palm
and sole, dorsal surface of
umbilicus, glans penis,
inner surface of prepuce
PARTS OF HAIR
Hair has a implanted part called root
and a projected part called shaft.
The root is surrounded by a hair
follicle( a sheath of epidermis and
dermis), and is expanded at its
proximal end to form the hair bulb.
Each hair bulb is invaginated at its end
by the hair papilla( vascular connective
tissue) which forms the neurovascular
hilum of the hair and its sheath.
Hair grows at the hair bulb by
proliferation of its cells capping the
The arrectores pilorum muscles
(smooth muscle supplied by
sympathetic nerve) connect the under
surface of the follicles to the superficial
part of the dermis.
Contraction of this muscle leads to
erection of hair, squeezes out the
sebum and produces goose skin.
Growth rate-: 1.5-2.2mm/week
CLINICAL ANATOMY OF HAIR
Hair exhibit alterations in certain diseases. In malnutrition hairs
become thin, dry and sparse ; in hypothyroidism they become
coarse and dry.
Excessive growth of hair is called hirsutism occur in
Loss of hair is known as alopecia.
Sudoriferous or eccrine
glands or sweat gland are
distributed all over the
Except lips,glans penis
and nail bed.
Types-:2-: Eccrine and
PARTS OF ECCRINE SWEAT GLAND
Much abundant are distributed in almost
every part of skin.
Each gland is a single tube ,the deep
part which coiled into a ball.
The coiled part , called the body of the
gland, lies in the deeper part of corium
or in the subcutaneous tissue.
The straight part, called the duct
traverses the dermis and epidermis and
opens on the surface of the skin.
The glands are large in the axilla and
groin most numerous in palms and sole.
Merocrine in nature.(Produce thin
watery secretion without disintegration
of the epithelial cell).
Supplied by cholinergic sympathetic
Function-: 1)Regulation of body
temperature by evaporation of sweat.
2)Help in excreting body salt.
PARTS OF APOCRINE SWEAT GLAND
Confined to axilla,
eyelids(Moll’s glands , nipple
and areola of the
breast,perineal region, and
the external genitalia.
They are larger than eccrine
glands and produce a thicker
secretion having a
characteristic odour. They
develop in close association
with hair and their ducts
typically open into the distal
ends of the hair follicles.
Also merocrine in nature.
Regulated by dual autonomic
On average 1 litre of sweat is
secreted per day.
Producing an oily secretion are
widely distributed all over the
dermis of the skin except for
palm and sole.
Abundant in scalp , face,
aperture of the ear,nose,mouth
Small sacculated in
Made up of clusters about 2-5
Their ducts opens into the hair
With the exception of lips, glans
penis,inner surface of prepuce,
labia minora, nipple and areola
of the breast and tarsal glands
of the eyelids where the ducts
open on the surface of skin.
Holocrine in nature(Produce
their secretion by complete fatty
degenaration of the central cells
of the alveolus).
FUNCTION OF SEBACEOUS GLAND
Holocrine in nature
Secretion is under hormonal control, especially the androgens.
The oily secretion of the sebaceous glands is called sebum.
Lubricates the skin and protects it from moisture , desiccation, and the
harmful sunrays. Sebum also lubricates hair and prevent them from
Sebum is also bactericidal in action.
Makes the skin water proof.
Water evaporates from the skin but the fats and oils are absorb by it.
CLINIICAL ANATOMY-:1) Excessive oiliness of the skin due to over
activity of the sebaceous glands is called seborrhoea.
Acne vulgaris is a common complication of seborrhoea.
Sebaceous cyst is common in scalp. It is due to obstruction of the
duct of a sebaceous gland caused either by trauma or infection.
FUNCTION OF THE SKIN
1)Protection-: Skin protects the body from mechanical injuries,
bacterial infection, heat and cold, wet and drought, acid and alkali and
the actinic rays of the sun.
2)Sensory-: Skin is sensory to touch, pain and temperature.
3) Regulation of body temperature-: Heat is lost through evaporation
of the sweat;and heat is conserved by the fat and hair.
4) Absorption-: Oily substances are freely absorbed by the skin.
5) Secretion-: Secrete sweat and sebum.
6)Excretion-: The excess of water, salts and waste products are
excreted through the sweat.
7)Regulation of Ph-: A good amount of acid is excreted through the
8) Synthesis-: In the skin Vit.D is synthesized from ergo sterol by the
action of ultra violate rays of the sun.
9)Storage-: Stores chloride.
10) Reparative-: The cuts and wounds of the skin are quickly healed.
Definition-: Is a general
coating of the body.
Definition-: Is a general coating of the body beneath the skin made up
of loose areolar tissue with varying amounts of fat.
Important features-:1) More distinct in the lower part of the anterior
abdominal wall,perinium and the limbs.
2) It is very thin on the dorsal aspect of the hands and feet ,sides of
the neck, face and around the anus.
3)Very dense on the scalp , palms and soles.
4)Superficial fascia shows stratification (into 2 layers) in the lower part
of anterior abdominal wall,perinium and upper most part of the thighs.
5) It contains-: a) Subcutaneous muscles in the face , neck and
b) Mammary gland c) Deeply situated sweat glands d) Localized
groups of lymph nodes e) Cutaneous nerves and vessels.
Function->1) Facilitates movements of the skin.
2)Serves as soft medium for passage of vessels and nerves.
3) Conserves body heat because fat is a bad conductor of heat.
Definition-: Is a fibrous sheet which invests the body beneath
the superficial fascia. It is devoid of fat, and is usually inelastic
Distribution-:1) Best defined in limbs where it forms tough and
2) Ill defined on the trunk and face.
of the deep fascia form:
a) The inter muscular septa
which divide the limb into
b) Fibroareolar sheath for the
muscles, vessels, nerves.
2) Thickening of the deep
fascia form: Retinacula
around certain joints like
wrist and ankle.
d) Palmar and plantar
aponeuroses for the for the
protection of nerves and
3) Interruptions in the deep
fascia on the subcutaneous
FUNCTION OF DEEP FASCIA
1) Keep the underlying structures in position.
2) Preserves the characteristic contour of the limb and neck.
3) Provides extra surface for muscular attachments.
4) Helps in venous and lymphatic return.
5) Assist muscles in their action by degree of tension and
pressure it exerts upon their surfaces.
6) The retinacula acts as a pulley and serve to prevent the loss
7) Synovial sheath of the tendon minimizes the friction.