9th lesson Medical students Medical Biology
Connective Tissue
Classification of connective tissue:It is classified according to components into:
҉ Embryonic connective tissue which is classified into :
-Msenchymal connective tissue.
Mucous connective tissue.-
҉ Connective tissue proper, which is classified into:
A-Loose (areolar) connective tissue.
B-Dense connective tissue, which is classified into:
1-Dense irregular connective tissue.
2-Dense regular connective tissue. It has two types"
a--Collagenous White regular dense
b--Elastic Yellow dense regular
Classification of connective tissue according to function into:
a-Adipose tissue.
b-Reticular tissue.
c-Pigment tissue.
d-Specialized connective tissue, which is classified into:
1-Cartilage.
2-Bone.
3-Blood.
Embryonic connective tissue, which is classified into:
-Mesenchymal connective tissue: is the connective tissue embryo, consists of mesenchymal cells in a gel – like amorphous ground substance containing scattered reticular fibers. The mesenchymal cell posses an oval nucleus contains fine chromatin network and prominent nucleoli.
-Mucous (Wharton's jelly): it is found in umbilical cord as Wharto's jelly, it contains satellite fibroblasts, few macrophages and some lymphocytes. The ground substance is soft and jelly like containing fine collagenous fibers.
Loose connective tissue: Gel-like with two fiber types; cells: fibroblasts, macrophage, mast cell, and some white blood cells. It's location is widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes.
Dense connective tissue: which is regular and irregular: it is chiefly characterized by the close packing of its fibers. It occurs in the form of sheets, bands and cord like structures e.g. dermis, capsules of certain organs, ligaments and tendon.
Dense irregular arranged connective tissue: Primarily irregularly arranged collagen fibers; some elastic fibers; major cell type is the fibroblast. It's location in dermis of the skin; fibrous capsules of organs and of joints.
Dense regular arranged connective tissue: Primarily parallel collagen fibers; a few elastic fibers; major cell types is the fibroblast. It's location in tendons, most ligament and shoulder joint. Dense regular has two types:
a-Collagenous White regular dense connective tissue: e.g. tendon (which connect the muscle with bone, it composed almost entirely of white fibrous tissue, the white (collagen) fibers are parallel and closely packed in bundles appear homogenous. Modified fibroblasts (tendon cells) are present.
b-Elastic Yellow dense regular connective tissue: parallel elastic fibers, some collagen many fibroblasts. It's location is in tendon, and ligaments.
Adipose tissue: Matrix as in areolar, but very spares; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet. It's location is under skin; around kidneys and eyeballs.
There are two types of adipose tissue: -White adipose tissue: it is normal body fat, very large spherical cells. It contains single fat droplet with cytoplasm. Nucleus pushed to one side of cell and flattened by accumulated fat.
- Brown adipose tissue: cells are smaller than those of white adipose tissue. The cytoplasm contains lipid droplet of varying size and also contains extraordinary large number of mitochondria. It is highly vascular with blood vessels.
Reticular tissue: it consists of reticular cells, these are star in shape, has long cytoplasmic extensions and the network of reticular fibers formed by them. Most of connective tissue contain reticular fibers which appear to join with lymph nodes and nodule and spleen.
Pigmented tissue: it occurs in animals and human, it presents in choroids and iris of the eye and in dark skinned races.