1. THE MUSCULAR TISSUE & THE LYMPHOID TISSUE PRE-LAB.6. BY PROF. DR. ANSARI Saturday, December 12, 2015

2. 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. Saturday, December 12, 2015

3. SKELETAL- SMOOTH – CARDIAC MUSCLES Saturday, December 12, 2015

4. 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. Saturday, December 12, 2015

5. 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. Saturday, December 12, 2015

6. Observe the alternate dark and light bands & peripherally situated multiple nuclei Saturday, December 12, 2015 This is a longitudinal Section of skeletal muscle fibers

7. The connective tissue over the muscular tissue Perimysium is a layer of connective tissue around the muscle. Saturday, December 12, 2015

8. Endomysium loose connective tissue called "endomysium" surrounds each muscle fiber. Saturday, December 12, 2015

9. Epimysium It is a layer of connective tissue enwrapping the whole muscle. Saturday, December 12, 2015

11. In a T.S. of skeletal muscle the nuclei are peripherally situated Saturday, December 12, 2015

12. Smooth muscle 1. 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. Saturday, December 12, 2015

13. 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. Saturday, December 12, 2015

15. In T.S. of Cardiac muscle Nuclei are centrally situated In T.S. of Cardiac muscle Nuclei are centrally situated Purkinje fibers Are specialized Cardiomyocytes With pale cytoplasm & central nucleus Purkinje fibers Are specialized Cardiomyocytes With pale cytoplasm & central nucleus

16. 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. Saturday, December 12, 2015

18. Microscopically palatine tonsil The epithelial lining is nonkeratinized Stratified squamous. A crept is an identifying feature of tonsil. A lymphoid nodule is Also a lymphoid feature. Saturday, December 12, 2015

19. 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. Saturday, December 12, 2015

21. Medulla The following sinuses are seen in lymph node:- Sub capsular sinus Trabeculae sinuses Medullary sinuses. Saturday, December 12, 2015 1. Dense connective tissue capsule 2. Dense connective tissue trabeculae 3. Cortex 3a. Cortical nodules with germinal centers 3b. Para cortex 4. Medulla 4a. Medullary cords 4b. Medullary sinus 5. Sub capsular sinus

22. Thymus Microscopically thymus section shows the characteristic thymic corpuscles, Hassel’s corpuscles. It is the source for “T” lymphocytes. Cortex is darkly stained Medulla is pale in appearance. Saturday, December 12, 2015

24. 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. Saturday, December 12, 2015

25. 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. Saturday, December 12, 2015