MMB (014, 015) Practical of Skeletal Muscle Histology

Question 1

Collagen type of Reticular fibers ?

Answer 1

collagen III

Question 2

Name the stain used ,, and the fibers shown

Answer 2

-silver stain (black) ;

• Reticular fibres (collagen III)

Question 3

What cells synthesize Reticular fibers ?

Answer 3

special fibroblasts called reticular cells

Question 4

What is reticular connective tissue?

Answer 4

A type of connective tissue with a network of reticular fibres, made of collagen III

Question 5

Are Reticular fibres unique only to reticular connective tissue ?

Answer 5

no , but only in this type they are dominant

Question 6

Role of Reticular fibers in skeletal muscle support ?

Answer 6

The reticular fibres in the endomysium → mechanical support for the individual muscle cells

Question 7

Other sites of reticular connective tissue ?

Answer 7

• Supporting framework for soft organs like the spleen, liver, lymph nodes, and bone marrow

Question 8

Define the tissue type an the fibers surrounding it

Answer 8

• Adipocytes surrounded by reticular fibres.

-On a reticulin stain, each adipocyte is outlined by reticulin (arrow)

Question 9

Are the arterioles surrounded by reticular fibres?

Answer 9

Yes

Question 10

Answer 10

Question 11

Answer 11

Question 12

Answer 12

Question 13

Answer 13

Question 14

What type of muscle is the external anal sphincter made of?

Answer 14

• Voluntary

• Skeletal muscle

Question 15

Answer 15

Question 16

Answer 16

B. muscle spindle

Question 17

Answer 17

Question 18

• Which muscle cell organelle of is responsible for calcium storage?

Answer 18

sarcoplasmatic reticulum

Question 19

Answer 19

•Variation in muscle fiber size

•Expansion of the endomysium by collagen

Question 20

Answer 20

Duchenne muscle dystrophy :

Extensive replacement of muscle by fat cells

Question 21

1- What is the nature of this disease?

Answer 21

An autoimmune disease.

Question 22

2- Mention the Pathogenesis.

Answer 22

Autoantibodies directed against acetylcholine “nicotinic” receptors. These antibodies impair Neuromuscular transmission with resultant muscle weakness.

Question 23

3- Mention the treatment

Answer 23

Cholinesterase inhibitors

Question 24

1- What is your Diagnosis?

Answer 24

Duchenne Muscle Dystrophy

Question 25

2- Describe the microscopic picture.

Answer 25

Marked variation in myofibers size, and endomysial fibrosis

Question 26

3- What is the IHC stain used in this case? Please interpret its results as shown in the figure.

Answer 26

Dystrophin IHC stain ;

Absence of the normal sarcolemmal staining (negative)

Question 27

4- Mention the difference between DMD and BMD.

Answer 27

BMD is generally milder than DMD, and the onset of symptoms usually occurs later Dystrophin levels in BMD are generally 30-80% of normal, while in DMD, the levels are less than 5%