CONNECTIVE TISSUE SCHOOL OF ANATOMICAL SCIENCES Connective consists - - PowerPoint PPT Presentation

CONNECTIVE TISSUE

SCHOOL OF ANATOMICAL SCIENCES

Connective consists of cells, fibres and ground substance. The cells produce the fibres and ground substance, which together are known as matrix. Connective tissue is classified according to the matrix:

• With a solid matrix – cartilage and bone.
• With a semi-solid matrix – connective tissue proper.
• With a fluid matrix – blood and lymph.

In this demonstration note the special staining techniques used to demonstrate specific features.

SEMI-SOLID MATRIX

Slide 120 (400x): Mesentery spread – rat (H, acid fuchsin and elastic)

Loose Areolar Connective Tissue

The rat from which this connective tissue spread was taken had been injected with India ink (carbon particles). NOTE:

• The macrophages filled with ingested carbon particles * in their

cytoplasm.

• The large, round metachromatic-staining granules of mast

cells.

• The large round pale nuclei of the mesothelial cells.
• Thin, dark, branched elastic fibres.

Question

• What is the importance of macrophages in connective tissue?

400x 1000x

*

Slide 120 (400x): Mesentery spread – rat (H, acid fuchsin and elastic)

Loose Areolar Connective Tissue – Mast Cells

NOTE:

• The large, round metachromatic-staining granules of mast

cells.

• The large, round, pale nuclei of mesothelial cells.
• The thick eosinophilic collagen fibres.
• Thin, dark, branched elastic fibres.

Question

• What is the importance of mast cells in connective tissue?

400x 1000x

Slide 122 (400x): Non-lactating mammary gland (H&E)

Dense Irregular Connective Tissue

NOTE:

• The irregularly arranged, broad eosinophilic collagen (type?) fibres.
• The relatively few, basophilic and flat fibroblast nuclei lying in close

apposition to the fibres; and

• A capillary * with a simple squamous endothelial lining.

Questions

• What is the function of dense irregular connective tissue?
• What is the function of fibroblasts in connective tissues?

1000x 400x

* *

Slide 122 (400x): Non-lactating mammary gland (H&E)

Adipose Tissue

NOTE:

• The many adipocytes with large clear spaces.
• The thin rim of eosinophilic cytoplasm.
• The flattened basophilic nuclei pushed to the

periphery.

• Loose connective tissue between adipocytes.
• Dense irregular CT at the top of the field.

Questions

• What is contained within the spaces in living

Adipose tissue?

• What type of fibres are found in the CT between

adipocytes?

• What is the function of adipose tissue?

Slide 50 (400x): Musculo-tendinous junction (H&E)

Dense Regular Connective Tissue

Compare with the dense irregular connective tissue (DICT) i.e. non-lactating mammary gland (slide 122). NOTE:

• The parallel arrangement of the eosinophilc

collagen (type?) fibres.

• The flattened basophilic fibroblast nuclei lying

between the collagen fibres. Questions

• Why are the fibres arranged in parallel?
• Is this tissue vascular?

Supplementary slides:

Slide 28 (400x): Aorta (Weigert’s elastic technique)

Elastic Tissue e.g. Aorta

In this section, NOTE:

• The concentrically arranged, blue-stained elastic

sheets in the wall of the aorta.

• The elastic fibres which cross-connect the elastic

sheets.

• The nuclei of the fibroblasts which secrete the

elastin have not been stained. Question

• What is the significance of highly developed

elastic tissue in large arteries such as the aorta?

Slide 25 (400x): Liver (Silver impregnation)

Reticular Tissue e.g. Liver

In this section, NOTE the fine, black-stained reticular fibres woven around the cords of liver cells to form a supportive ‘basket’. They have been stained specifically by means of a special (silver) technique. Questions

• Can reticular fibres be distinguished in routine H

& E sections by their staining reaction or structural features? Explain your answer.

SOLID MATRIX

Slide 32 (400x): Trachea (H&E)

Hyaline Cartilage

NOTE:

• The gradual transition from the eosinophilic,

dense fibrous connective tissue of the perichondrium * to a rigid cartilaginous matrix.

• The chondrocytes which are either isolated or

in nests; and

• The basophilic cartilaginous matrix.

Questions

• Why is the cartilage matrix basophilic?
• What evidence do you have in this field of

appositional and interstitial growth?

• How are chondrocytes nourished?
• What function does the cartilage serve in the

trachea?

*

Slide 79 (400x): Meniscus of the knee (H&E)

Fibrocartilage

NOTE:

• The presence of chondrocytes in lacunae *

which are arranged at random, either singly or in clusters between eosinophilic collagen fibres. Questions

• Why does fibrocartilage have such a high

proportion of collagen fibres? Why is it called ‘fibrocartilage’?

• Where does fibrocartilage occur? What is its

function there?

• How does fibrocartilage ‘grow’?
• How is cartilage nourished?

* *

Slide 1 (100x): Long bone (Decalcified, H&E)

Compact Bone

This is a transverse section through long bone. NOTE:

• The arrangement of lamellae in the bone

matrix.

• The Haversian systems/Osteons.
• The periosteum covering on the left side of the

bone.

• Sharpey’s fibres inserting into the bone at the

top of the field.

• A Volkmann’s canal *.
• Lacunae in the bone matrix.

Questions

• Why is bone considered a connective tissue?
• What are the functions of the different bone

cells?

• What is the main organic component in bone

matrix?

• What are the inorganic salts responsible for

bone hardening?

• What is the function of the periosteum,

endosteum and Sharpey’s fibres?

*

Slide 3 (400x): Long bone (Ground bone & silver impregnation)

Compact Bone

This transverse section through a long bone shows an Haversian system. NOTE:

• The lacunae in the concentric lamellae of the

Haversian system; and

• The canaliculi radiating from the lacunae.

Questions

• What is a lacuna? And what is its function?
• How do the osteocytes in the lacunae of the outer

lamellae of the Haversian system obtain their nourishment?

• What is meant by a Haversian system?
• What do Haversian canals contain in living bone?
• Is there any evidence of osteocytes in lacunae in

this field?

• How is it that bone has a lamellar structure?
• How are the lamellae arranged in this compact

bone?

• Explain the presence of interstitial lamellae.
• What is the function of the Volkmann’s canal in

living bone?

• How was the section on this slide prepared?

Slide 67 (400x): Nasal cavities & air sinus (Decalcified, H&E)

Spongy (Cancellous) Bone

This field shows a trabeculum of eosinophilc spongy (cancellous) bone from the nasal cavity. NOTE:

• The parallel lamellae.
• The endosteum with fibroblast nuclei lining the

marrow cavity.

• The osteocytes in lacunae.

Questions

• What does the word ‘trabeculum’ mean?
• Describe the contents of the marrow spaces.
• How does the spongy bone differ in structure from

compact bone?

Supplementary slide:

Slide 51 (400x): External auditory meatus (H&E and elastic)

Elastic Cartilage

In this section, NOTE:

• The features which this type of cartilage shares

with hyaline cartilage.

• The branching elastic fibres, which form a dense

network throughout the matrix. Question

• What function does this cartilage serve in the

external auditory meatus?

FLUID MATRIX

Slide 70 (1000x): Blood smear (Romanowsky & Leishman’s)

Blood: Eosinophil

Eosinophils constitute 2-4% of circulating

• leucocytes. NOTE:
• The size – 1.5x larger than an erythrocyte.
• The bi-lobed nucleus.
• The large, eosinophilic, spherical refractile

granules – all approximately the same size. Question

• What are the functions of eosinophils?

Slide 70 (1000x): Blood smear (Romanowsky & Leishman’s)

Blood: Neutrophil

Neutrophils constitute 60-70% of circulating

• leucocytes. They are 12-15µm in diameter, with a

nucleus consisting of 2-5 (usually 3) lobes linked by fine threads of chromatin. In females, the inactive X-chromosome appears as a drumstick-like appendage as one of the lobes of the nucleus although this is not obvious in all neutrophils. NOTE:

• The size of the neutrophil –larger than an erythrocyte.
• The multi-lobed nucleus with clumped chromatin.
• The ‘drumstick’ i.e. Barr Body and the fine

neutrophilic granules in the cytoplasm. Question

• What is the function of neutrophils?

Slide 70 (1000x): Blood smear (Romanowsky & Leishman’s)

Blood: Basophil

Basophils make up less than .1% of blood leucocytes and are therefore difficult to locate in smears. NOTE:

• The size – slightly larger than an erythrocyte.
• The nucleus – obscured by the overlying basophilic granules.
• The irregular shape of the granules.
• The presence of a lymphocyte *.

Question

• What do the basophilic granules contain?

*

Slide 70 (1000x): Blood smear (Romanowsky & Leishman’s)

Blood: Monocyte & Eosinophil

NOTE:

• The size of the monocyte – very large.
• The large, basophilic nucleus.
• The pale, basophilic, frosted-glass appearance of

the cytoplasm. Question

• To what connective tissue cells do monocytes

give rise?

Slide 70 (1000x): Blood smear (Romanowsky & Leishman’s)

Blood: Lymphocyte & Platelets

Lymphocytes are spherical cells classified according to the site

• f differentiation i.e. bone marrow or thymus. NOTE:
• The size – slightly larger that an erythrocyte.
• The large, darkly stained nucleus with fairly clumped

chromatin.

• The thin rim of basophilic cytoplasm.
• The basophil * next to the lymphocyte.
• The clusters of platelets **.

Question

• What are the functions of lymphocytes?
• What is the function of platelets? From which cell are they

derived?

* **