the muscular tissue & the lymphoid tissue pre-lab.6. by prof. dr. ansari saturday, december 12,...

THE MUSCULAR TISSUE &

THE LYMPHOID TISSUEPRE-LAB.6.

BYPROF. DR. ANSARI

Saturday, April 22, 2023

The objectives

• To know the histological structure of muscular tissue.

• To differentiate between the smooth muscle, skeletal muscle & cardiac muscle microscopically.

• To learn the histology of various lymphoid organs.

• To distinguish one from the other lymphoid organs histological.


SKELETAL- SMOOTH – CARDIAC MUSCLES


Features of muscular tissue• Cells are called as myocytes, occur as sheets or

fibers.• The tissue possess the contractile elements, actin

and myosin proteins.• They show regular and irregular arrangements of

actin and myosin filaments.• Skeletal and cardiac muscles show birefringence,

or striated in nature.• There is no mitosis in skeletal and cardiac

muscles hence no regeneration.


Skeletal muscle

• It is striated muscle fibers.• Multinucleated & nuclei are peripherally

situated.• It is voluntary muscle, also called as skeletal

muscle.• It show striations in their cytoplasm, these are

due to alignment of actin and myosin filaments in register.


Observe the alternate dark and light bands & peripherally situated multiple nuclei


This is a longitudinal Section of skeletal muscle fibers

The connective tissue over the muscular tissue

• Perimysium is a layer of connective tissue around the muscle .


Endomysium

• loose connective tissue called "endomysium" surrounds each muscle fiber.


Epimysium

• It is a layer of connective tissue enwrapping the whole muscle.


In a T.S. of skeletal musclethe nuclei are peripherally situated


Smooth muscle1. Smooth muscles are found in the walls of blood vessels, stomach, intestines, uterus and urinary bladder .2.The muscle fibers are spindle shaped.3. A large oval shaped nucleus is situated centrally in the spindle shaped smooth muscle fiber.4. No striations are seen in these muscle fibers.


Cardiac muscle

• It is striated muscle.• It is involuntary muscle.• It is seen in heart.• It shows intercellular cell junctions, called as intercalated disks.• The cardiac muscles show branching fibers.• The nucleus is situated centrally.



In T.S. ofCardiac muscleNuclei are centrally situated

In T.S. ofCardiac muscleNuclei are centrally situated

Purkinje fibersAre specializedCardiomyocytesWith pale cytoplasm& central nucleus

Purkinje fibersAre specializedCardiomyocytesWith pale cytoplasm& central nucleus

Lymphoid organs

• Palatine tonsil are situated in the oral cavity• Thymus is situated in the neck and superior

mediastinum.• Lymph nodes are situated in the neck, axilla,

groin, & abdomen• Spleen is located in the left hypochondrium.• These organs protect us from foreign invaders,• They form second line of defense.


Microscopically palatine tonsil

• The epithelial lining is nonkeratinizedStratified squamous.A crept is an identifying feature of tonsil.A lymphoid nodule is Also a lymphoid feature.


Lymph node

• A lymph node has a hilum, where blood vessels enter and leave.

• It has a capsule covering.• It has a cortex and medulla zones.• It shows a sub cortical sinus.• It has Lymphoid follicles in cortex.• The Para cortex is deep cortex having “T”

lymphocytes.• The germinal centers have “B” lymphocytes.


Medulla

• The following sinuses are seen in lymph node:-

• Sub capsular sinus• Trabeculae sinuses• Medullary sinuses.


1. Dense connective tissue capsule2. Dense connective tissue trabeculae 3. Cortex3a. Cortical nodules with germinal centers 3b. Para cortex 4. Medulla 4a. Medullary cords4b. Medullary sinus5. Sub capsular sinus

1. Dense connective tissue capsule2. Dense connective tissue trabeculae 3. Cortex3a. Cortical nodules with germinal centers 3b. Para cortex 4. Medulla 4a. Medullary cords4b. Medullary sinus5. Sub capsular sinus

Thymus• Microscopically thymus section shows the characteristic thymic corpuscles, Hassel’s corpuscles.• It is the source for “T” lymphocytes.Cortex is darkly stainedMedulla is pale in appearance.


Spleen• It is the largest lymphoid

organ.• Microscopically it shows

“white pulp & Red pulp”.• Red pulp is due to blood

vessels.• White pulp is due to

lymphoid tissue.• Eccentrically situated

efferent arteriole is a special feature of spleen corpuscles.


Applied anatomy• Myasthenia gravis is a disease of weakness of

muscle.• Duchene's muscular dystrophy is a degenerating

congenital disorder of muscular system.• Tonsillitis is an inflammation and infection of

palatine tonsils.• Lymph nodes are involved in spread of cancer.• HIV virus will damage “T” lymphocytes. • In myocardial infarction there is damage to

cardiac muscles.


the muscular tissue & the lymphoid tissue pre-lab.6. by prof. dr. ansari saturday, december 12,...

Documents

skeletal muscle cardiac

involuntary muscle

striated muscle fibers

smooth muscle fiber

layer of connective

skeletal muscleit

muscular tissue perimysium

smooth muscles