Histology 🔬

Question 1

Answer 1

Hyaline cartilage (H & E)

• Irregular collagenous fibers of the outer fibrous layer of the perichondrium.
• The chondrocytes appear single or as cell nests in the lacunae.
• The matrix is homogenous basophilic.

Question 2

Answer 2

Yellow elastic fibro-cartilage (H & E)

• The skin is found on both sides.
• A plate of yellow elastic fibrocartilage is found between the two layers of skin.
• The matrix is rich in elastic fibers.

Question 3

Answer 3

Yellow elastic fibro-cartilage (Ver-Hoeff’s stain)

• The skin is found on both sides.
• The plate of elastic fibrocartilage shows black-stained matrix due to rich elastic fibers.

Question 4

Answer 4

White fibro-cartilage (H & E)

• No perichondrium.
• Rows of chondrocytes which are separated by acidophilic collagenous bundles.

Question 5

Answer 5

Decalcified compact bone (H & E)

• The most characteristic point is the presence of Haversian systems (osteons) with their concentric acidophilic bone lamellae.
• The osteocytes are regularly arranged between the lamellae.

Question 6

Answer 6

Spongy (cancellous) bone (H & E)

• No typical Haversian systems.
• The bone is arranged in the form of branching and anastmosing bars enclosing between them bone marrow spaces which are filled with red (active) bone marrow.

Question 7

Answer 7

Intra-cartilagenous ossification (H & E)

• Presence of different zones of ossification
• In zone of calcification; the osteoblasts deposit acidophilic bone matrix over the basophilic bars of calcified cartilage matrix

Question 8

what are the stages of intra-cartilaginous ossification?

Answer 8

1. Stage of resting cartilage
2. Stage of proliferation
3. Stage of maturation and hypertrophy
4. Stage of calcification
5. Stage of Invasion
6. Spongy bone formation
7. Stage of remodeling and compact bone formation

Question 9

Answer 9

Skeletal muscle (L/S)

• Muscle fibers are large& cylindrical with multiple peripheral elongated & ovoid nuclei.
• Prominent transverse striations.

Question 10

Answer 10

Skeletal muscle (T/S)

• Formed of bundles of muscle fibers.
• The fibers are large, polyhedral, with peripheral nuclei and acidophilic myofibrils in the sarcoplasm.

Question 11

Answer 11

Skeletal muscle (Phosphotungstic acid)

• The skeletal muscle transverse striations are clearly seen.

Question 12

what are the characters of zone of calcification in Intra-cartilagenous ossification?

Answer 12

In zone of calcification; the osteoblasts deposit acidophilic bone matrix over the basophilic bars of calcified cartilage matrix