Connective tissue (1) 1.Loose connective tissue (No.4, No.1 ) 2.Dense connective tissue (No.14) 3.Adipose tissue (No.14/ No.6) 4.Reticular tissue (No.6)

1. General features: 1) small number of cells and large amount of extracellular matrix (intercellular material). 2) the extracellular matrix is composed of fibers and an amorphous ground substance. 3) functions: connection, supporting, protecting, nutrition, defense and repairing.

2. Classification Connective tissue proper Cartilage Bone blood The types of CT are determined on the basis of the types of cell and the characteristics of the extracellular matrix

connective tissue proper CT in narrow sense means connective tissue proper, include: loose CT adipose tissue reticular tissue dense CT

Loose connective tissue Material: rabbit mesentery Slide No:4 High power: 1. Elongated and tortuous collagenous fibers are stained red and arranged in bundles. 2. The elastic fibers are blue stained, branched and formed a woven network. 3. The fibroblast is the cell most commonly in close to the collagen fiber. Its basophilic nucleus is visible. 4. For the macrophage, its cytoplasm contains some blue dye substance. LCT：HE X400

fiber Low power: fibers are loosely and irregularly arranged. high power: Elongated and tortuous collagenous fibers are stained red and arranged in bundles. Elastic fibers are blue stained,branched and formed a woven network.

Cell Macrophage: ingest the blue dye by phagocytosis so they can be easily identified. Fibroblast: the most commonly cell in close to the collagen fiber.only the basophilic nucles is visible,but the acidophilic cytoplasm is not clearly defined.

Fibroblast Macrophage

The lightly stained submucosa between mucosa and smooth muscle layer. Slide No:1 Method: H.E lower power: The lightly stained submucosa between mucosa and smooth muscle layer. Small intestine: HE X40

Low power： 1 submucosa

Fibroblast collagenous fibers High power: collagenous fibers are the predominant component and they course in different direction. They are sectioned in various planes and cut ends is seen. stained red and arranged in bundles. Fibroblast Fibroblast are the most numerous cells ,only the basophilic nucles is visible,but the acidophilic cytoplasm is not clearly defined. collagenous fibers Small intestine: LCT HE X400

Dense connective tissue and adipose tissue Slide No:14 Material: human skin from finger Method: H.E Naked eye: in the section, epidermis is violent stained. Under epidermis, the dermis is pink and composed of dense connective tissue. In hypodermis, you can find loose connective tissue and adipose tissue. Skin :DCT HE X40

Low power: In the section , epidermis is violent stained. Under epidermis,the dermis is pink and compose of denes connective tissue. epidermis dermis

high power: collagenous fibers are the predominant component and they course in different direction. They are dense ,irregularly arranged and formed thic bundles. stained red .The numbers of cells are few, most of which are fibroblasts and fibrocytes.

Dense regularly connective tissue High power: Collagenous fibers are arranged in compact,parallel bundles Tendon cell: Tendon(longitudinal section)

Reticular tissue Slide No.5 Material: lymph node of cat Method: H.E High power: Reticular cell: A reticular cell produces reticular fiber and surrounds the fibers with its cytoplasm. It has many processes. Its nuclei is lightly stained, but the nucleolus is clear. Lymph node: Reticular tissue HE X400

Reticular tissue Lymph node: Reticular tissue HE × 400

Reticular tissue ①reticular cell ②lymphocyte ③macrophage

Lymph node: Reticular tissue Silver × 400

Adipose tissue Slide NO: 6 Material: human lymph node Method: H&E Low power: Fat cell are present in large accumulations, orgnized into adipose tissue Lymph node：Adipose tissue HE X40

high power: Individual Fat cells show their chracteristic structure,empty cells,due to solution of fat during section preparation. The nucleus is pushed to the periphery of the cell.

Fibroblast Macrophage

Mast cells 1.Round and large cell 2.Small dark-stained nucleus 3.Basophilic secreting granules--metachromatically

Plasma cell 1.Round or ovoid in shape 2.Nucleus with more clock-liked heterochromatin which located eccentrically 3.Basophilic cytoplasm

Collagenous fibers collagenous fibril

fibroblast Plasma cell Mast cell macrophagy

The drawing Loose connective tissue H&E stain 400× Collagenous fiber Macrophage Elastic fibers Fibroblast Loose connective tissue H&E stain 400×