Download presentation
Presentation is loading. Please wait.
Published byKimberly Farmer Modified over 9 years ago
1
Dr. ANAND SRINIVASAN
2
Made of tissues and organs made of lymphocytes. Concerned with immunity Made of : Immunoglobins Lymphocytes Natural Killer cells Macrophages & cells of mononuclear phagocytic Antigen presenting cells Neutrophils, mast cells & eosinophils
3
LYMPHOID TISSUE DiffuseDenseMALTDiscrete Thymus Lymph node SpleenTonsil
4
Made of connective tissue & lymphocytes Covered by capsule Trabeculae / interlobular septum carrying neurovascular structures. Reticulum supporting the cellular parenchyma
5
Central lymphoid organ Bilobed, unequal size Superior & Anterior mediastinum Dual origin “Lympho – epithelial organ” Lymphocytes Mesoderm Epithelial reticular cells Endoderm Well developed in foetus & early childhood Peak development – puberty; later involutes Only Efferent lymphatics; No Afferent lymphatics
6
Presence of Capsule, Inter lobular septa with blood vessels Darkly stained cortex and lightly stained medulla Presence of “Hassal’s bodies” made of central hyaline material and surrounded by flat epithelial cells Number & calcification of Hassal corpuscles increases with age Presence of Cellular cytoplasmic reticulum / Epithelial Reticular cells (This is different from reticulum of other lymphoid organs which are formed by reticular fibers) which secrete Thymosin and thymopoietin.
8
Oval or bean shaped structures Serve as filters Usually found in groups Afferent and efferent vessels
9
Presence of thin capsule and trabeculae Presence of subcapsular sinus (made of reticular fibers and cells) continuous with trabecular sinus which in turn continuous with medullary sinus Presence of lymphatic nodule with / without germinal centers(primary & secondary nodules). Presence of medullary cord and medullary sinus
12
Largest lymphoid organ Upper left part of abdominal cavity Functions Foetal life : Blood formation Postnatal : destroys old RBC, filters blood from antigens & microorganism.
13
Capsule covered by mesothelium (peritoneum) Capsule contains few smooth muscle fibers (Spleen as reservoir of blood) Thick trabeculae carrying neurovascular bundles Presence of “white pulp” and “Red pulp”
14
WHITE PULP (Malpighian bodies ) Lymphoid aggregation (PALS)around central artery. Central A. then enters red pulp as “Penicillar arteries” RED PULP Presence all blood cells Composed of Splenic cords of Bilroth Splenic venous sinuses
18
GENERAL FEATURES: Located in oropharynx between palatoglossal and palatopharyngeal arches. Medial surface – crypts. HISTOLOGICAL FEATURES: Crypts are lined by stratified squamous epithelium Lymphatic nodules in the lamina propria
20
Chapter 9 – Microanatomy Workbook, RAKMHSU
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.