Histology of Spleen by Dr. Rabia I. Gandapore.pptx

Histology of Spleen

1. Histology Of Spleen Dr. Rabia Inam Gandapore Assistant Professor Head of Department Anatomy (Dentistry-BKCD) B.D.S (SBDC), M.Phil. Anatomy (KMU), Dip. Implant (Sharjah, Bangkok, ACHERS) , CHPE (KMU),CHR (KMU), Dip. Arts (Florence, Italy )

2. Teaching Methodology LGF (Long Group Format) SGF (Short Group Format) LGD (Long Group Discussion, Interactive discussion with the use of models or diagrams) SGD (Short Group) SDL (Self-Directed Learning) DSL (Directed-Self Learning) PBL (Problem- Based Learning) Online Teaching Method Role Play Demonstrations Laboratory Museum Library (Computed Assisted L earning or E-Learning) Assignments Video tutorial method

3. Goal/Aim (main objective) To help/facilitate/augment the students about the: 1. Describe the histological features and functions of spleen .

4. Specific Learning Objectives (cognitive ) At the end of the lecture the student will able to: Recognize the Histological features of the Spleen & function Sketch labeled Histological diagram of the Spleen

5. Psychomotor Objective: (Guided response ) A student to draw Histological labelled diagram of the Spleen.

6. Affective domain To be able to display a good code of conduct and moral values in the class. To cooperate with the teacher and in groups with the colleagues. To demonstrate a responsible behavior in the class and be punctual, regular, attentive and on time in the class. To be able to perform well in the class under the guidance and supervision of the teacher. Study the topic before entering the class. Discuss among colleagues the topic under discussion in SGDs. Participate in group activities and museum classes and follow the rules. Volunteer to participate in psychomotor activities. Listen to the teacher's instructions carefully and follow the guidelines. Ask questions in the class by raising hand and avoid creating a disturbance. To be able to submit all assignments on time and get your sketch logbooks checked.

7. Lesson contents Clinical chair side question: Students will be asked if they know what is the function of Outline: Activity 1 The facilitator will explain the student's Spleen Activity 2 The facilitator will ask the students to make a labeled diagram of the spleen Activity 3 The facilitator will ask the students a few Multiple Choice Questions related to it with flashcards .

8. Recommendations Students assessment: MCQs, Flashcards, Diagrams labeling. Learning resources: Langman’s T.W. Sadler, Laiq Hussain Siddiqui, Snell Clinical Anatomy , Netter’s Atlas , BD Chaurasia’s Human anatomy, Internet sources links.

9. Spleen Splenic pulp Blood supply Function of spleEn

10. Spleen Largest Lymphoid Organ Location: Upper left Quadrant of abdominal cavity Only Lymphoid organ interposed in blood circulation Sinuses filled with blood , macrophages & dendritic cells in their wall due which it carries out immunologic filtration of blood by removing blood-borne antigen. Site for: 1. Destruction of old & worn out erythrocytes . 2. Production of activated lymphocytes

11. Covered by capsule of dense irregular connective tissue. Trabeculae extends from capsule into substance of organ & divides its parenchyma called Splenic pulp into incomplete compartments. Mammals: connective tissue of capsule & trabeculae contains large no. of smooth muscle fibres . Humans: smooth muscle fibres very small

12. Splenic Pulp Red pulp White Pulp

13. Splenic Pulp Splenic Pulp: Spaces between the trabeculae are occupied by sponge like tissue Naked eye section shows: White area: White Pulp Red area: Red Pulp

14. 1 . Red Pulp Contains huge number of E rythrocytes Microscopic examination: consists of cellular cords called Splenic cords separated from each other by venous sinuses called Splenic Sinuses

15. a. Splenic cords ( Billroth ) Contain cells supported by a fine meshwork of reticular fibres & reticular cells: Erythrocytes Lymphocytes Plasma Cells Granular leukocytes Platelets Macrophages Dendritic Cells

16. b . Splenic sinuses (sinusoids) Irregularly shaped wide venous sinuses that lies between splenic cords. Differ from ordinary sinusoids by: Lined by fusiform endothelial cells that are extremely long & parallel to longitudinal axis of sinus Between adjacent endothelial cells are present large gaps (2-3µm wide): Allows exchange between sinuses & cords Endothelial cells rest on incomplete basal lamina & supported by transversely arranged reticular fibres Macrophages of cords lie in vicinity of sinusoids

17. 2 . White Pulp Consists of typical lymphoid tissue that surrounds & follows branches of splenic artery , forming a cylindrical peri -arterial lymphatic sheath (PALS) around each branch (arteriole). PALS: Composed chiefly of T- Lymphocytes At places: enclosed within PALS are lymphoid nodules that are composed of B-Lymphocytes . At these places the peri -arterial lymphatic sheaths appear to be expanded in the form of ovoid or fusiform masses. Most of these l ymphatic nodules are secondary nodules that exhibit germinal centres (indicative of antigenic challenges) Each branch of the splenic artery that runs through a peri -arterial lymphatic sheath is known as a CENTRAL ARTERY

18. White pulp surrounded by Marginal Zone composed of diffuse lymphatic tissue that contains: T-lymphocytes B-Lymphocytes Plasma cells Macrophages Dendritic cells Marginal sinuses (Connected to central artery by narrow vascular channels

19. Histological Stains (H&E) White pulp: Darker stain ( Deep basophilic/purplish ) because contains densely packed lymphocytes Red pulp: lighter stain Eosinophilia: because of erythrocytes Basophilia : because of lymphocytes

20. Blood Supply of Spleen

21. Splenic artery enters spleen via HILUM Divides into branches known as TRABECULAR ARTERIES These branch & rebranch within trabeculae & leave when diameter reduced to 0.2mm i.e ARTERIOLES These enter white pulp known as CENTRAL ARTERIES surrounded by peri -arterial lymphatic sheath which is expanded in those regions which contains lymphatic nodules . In region of lymphatic nodules the central artery occupies a eccentric position since it lies away from germinal centre Central arteries gives off CAPILLARIES that supply white pulp & marginal sinuses.

22. After no. of divisions the central artery reduced in size and lose the investment of white pulp & enters the red pulp Here artery sub-divides into short & straight arterioles known as PENICILLAR ARTERIES PENICILLAR VESSELS ( Penicilli ) consists of 3 successive segments : First Segment: Longest called PULP ARTERY (Arteriole) possess thin coat of smooth muscle Second Segment: Divides further give rise to sheathed arteries (ELLIPSOIDS) surrounded by a fusiform sheath of macrophages. No smooth muscle Third Segment: Each sheathed artery divides into 2 or more TERMINAL ARTERIAL CAPILLARIES lined by a continuous layer of endothelium & transport blood to venous sinuses of red pulp

23. Theory Closed circulation theory: terminal arterial capillaries open directly into venous sinuses . Open circulation theory: terminal arterial capillaries release their blood into splenic cords from where blood slowly percolates into the venous sinuses

24. Veins Venous sinuses pour blood into pulp veins which unites to form larger trabecular veins that runs in connective tissue trabeculae . These veins consists only of endothelium supported by fibromuscular tissue of the trabeculae . Trabeculae veins drain into splenic vein

25. Functions of Spleen

26. Functions Immunological Filtration of blood: Defense centre against antigens that enters circulation & reacts promptly to remove antigens carried in blood . Owning to: Phagocytic cells T-Lymphocytes B-Lymphocytes Dentritic cells

27. Production of lymphocytes: white pulp site of production of lymphocytes , these migrate to red pulp & reaches blood stream by passing through the walls of splenic sinuses . Destruction of old & worn out erythrocytes: when normal life span 120 days completed: reaches spleen & phagocytosed & destroyed by macrophages of spleen Storage of blood: owing to spongy structure, splenic pulp acts as storehouse for blood . When needed smooth muscle fibres contracts & stored blood returns to circulation to increase circulating blood volume. Human storage capacity is small.

28. Thank You