Biology Today - February 2018

Loose Connective Tissue

It has loosely arranged cells in a semi-fluid ground substance.

Table: Types of loose connective tissue

Areolar tissue Adipose tissue Reticular tissue

Structure

It takes the form of fine threads crossing

each other in every direction leaving small

spaces called areolae. It consists of ground

substance, matrix, white and yellow

fibres and cells like fibroblasts, mast cells,

macrophages, lymphocytes, plasma cells,

mesenchyme cells, chromatophores. Fat cells

can be seen in small groups.

It is a fat storing connective tissue. This

tissue consists of several spherical or

oval adipose cells. Each adipose cell

contains fat globules, due to which

the nucleus and the cytoplasm are

displaced to the periphery. These cells

are often called signet ring cells.

This tissue consists of star-shaped

reticular cells whose protoplasmic

processes join to form a cellular

network. The reticular fibres are

present on the reticular cells. They

are composed of a protein called

reticulin. Matrix and some other cells

such as macrophages, lymphocytes

and adipose cells are also present.

Location

Most widely distributed connective tissue

in the body. It is present under the skin

as subcutaneous tissue in between and

around muscles, nerves and blood vessels

in submucosa of gastrointestinal tract,

respiratory tract, bone marrow.

Found in the subcutaneous tissue,

around the heart, kidneys, eyeballs,

mesenteries and omenta, where fat is

stored. It is found in blubber of whale

and elephant seal, hump of camel, fat

bodies of frog.

Liver, spleen, lymph nodes, thymus,

tonsils, bone marrow and lamina

propria of the gut wall.

Function

Binding parts together, provides

strength, elasticity, support to the parts

where this tissue is present. It also provides

rapid diffusion of materials and migration of

wandering cells towards areas of infection

and repair.

It is chiefly a food reserve or ‘fat

depot’ for storage. The subcutaneous

fat prevents heat loss from the body,

forms a shock-absorbing cushion

around the eye balls and kidneys.

Provides strength and support

and forms the supporting frame-

work (stroma) of many organs. It

also helps to bind together the cells

of smooth muscles. The reticular

cells are phagocytic and form de-

fence mechanism of the body.

Diagrammatic representation

Histocyte

Matrix

Mast cell

Fibroblast

Bundle

of white

fibres

Yellow

fibres

Nucleus

Cytoplasm

Matrix

Blood vessel

Adipose cell

Fat

globule

Dense Connective Tissue

This tissue contains tightly packed collagen fibres, making it stronger than loose connective tissue. It is of two types : dense irregular
connective tissue and dense regular connective tissue.

(i) Dense irregular tissue consists of fibroblasts and many fibres
(mostly collagen) that are oriented differently. This type of connective
tissue produces tough coverings that package organs, such as capsules
of kidneys and adrenal glands. It also covers muscle as epimysium,
nerves as perineurium and bones as periosteum.

(ii) Dense regular connective tissue has collagen fibres present
in rows between many parallel bundles of fibres. It is of two types as
discussed in the table on next page: