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Questions and Answers
Which component of the lymph node is primarily responsible for housing B lymphocytes?
Which component of the lymph node is primarily responsible for housing B lymphocytes?
What structure lacks lymphoid nodules and is characterized by an accumulation of T cells?
What structure lacks lymphoid nodules and is characterized by an accumulation of T cells?
What is the primary function of medullary cords in a lymph node?
What is the primary function of medullary cords in a lymph node?
Which of the following structures is part of the stroma of the lymph node?
Which of the following structures is part of the stroma of the lymph node?
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What role do macrophages play within the lymph node's inner medulla?
What role do macrophages play within the lymph node's inner medulla?
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What are the two main types of pulp in the spleen?
What are the two main types of pulp in the spleen?
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Which of the following structures is primarily found in the white pulp of the spleen?
Which of the following structures is primarily found in the white pulp of the spleen?
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The red pulp of the spleen is chiefly composed of which of the following?
The red pulp of the spleen is chiefly composed of which of the following?
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Which structure passes through the lymphatic nodules in the white pulp of the spleen?
Which structure passes through the lymphatic nodules in the white pulp of the spleen?
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What type of circulation occurs in the red pulp of the spleen?
What type of circulation occurs in the red pulp of the spleen?
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What do the trabeculae in the spleen primarily form?
What do the trabeculae in the spleen primarily form?
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Which type of lymphocytes is primarily associated with the periarteriolar lymphoid sheaths (PALS)?
Which type of lymphocytes is primarily associated with the periarteriolar lymphoid sheaths (PALS)?
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Which type of tissue fills the splenic cords of Billroth in red pulp?
Which type of tissue fills the splenic cords of Billroth in red pulp?
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What significant feature is present in the central artery of the spleen?
What significant feature is present in the central artery of the spleen?
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The splenic sinusoids are characterized as which type of space?
The splenic sinusoids are characterized as which type of space?
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Study Notes
Lymphatic Organs: Microscopic Structure
- Objectives: Understand the location of lymphatic organs, and the microscopic features of lymph nodes, spleen, thymus, and tonsils.
Lymph Node
- Stroma: Covered by a capsule, which extends inward to form trabeculae.
- Parenchyma: Divided into outer cortex, paracortex, and inner medulla.
- Cellular Components: Reticular cells, plasma cells, dendritic cells, macrophages, and lymphocytes of all types are abundant in lymph nodes.
Lymph Node: Outer Cortex
- Subcapsular Sinus: A sinus running between lymphoid nodules, arising from the subcapsular sinuses.
- Lymphoid Nodules: Can have or lack a germinal center, composed mostly of developing B lymphocytes and few helper T lymphocytes.
Lymph Node: Paracortex
- Lymphoid Nodules: Lacking lymphoid nodules, and an accumulation of T cells.
Lymph Node: Inner Medulla
- Medullary Cords: Composed of B lymphocytes, plasma cells, and macrophages.
- Medullary Sinus: Containing lymph, lymphocytes, and often many macrophages.
Spleen
- Stroma (Connective Tissue): Covered by a capsule with trabeculae, which partially subdivide the parenchyma. Trabeculae include trabecular arteries and veins.
- Parenchyma (Splenic Pulp): Lacks cortex and medulla, instead composed of white pulp and red pulp.
Spleen: White Pulp
- Lymphatic Nodules: Consists of lymphatic nodules with germinal centers.
- Central Artery: Passes through the lymphatic nodules, surrounded by PALS (periarteriolar lymphoid sheaths) consisting mostly of T cells.
Spleen: Red Pulp
- Splenic Cords of Billroth: Composed of reticular tissue with T and B lymphocytes, macrophages and red blood cells.
- Splenic Sinusoids: Blood vessels, where blood cells—of all types—are located within both cords and sinuses.
Thymus
- Stroma: Covered by a capsule which extends into trabeculae, creating incomplete lobules.
- Parenchyma: Each lobule is composed of an outer cortex and an inner medulla.
Thymus: Cortex
- Cellular Components: Contains more densely packed T lymphoblasts (thymocytes) and macrophages.
- Reticular Cells: Fewer epithelial reticular cells forms a cytoreticulum.
- Lymphatic Nodules: No lymphatic nodules.
Thymus: Medulla
- Cellular Components: Contains epithelial reticular cells.
- T Lymphocytes: Contains fewer densely packed differentiated T lymphocytes.
- Epithelial Reticular Cells: More epithelial reticular cells.
- Thymic Corpuscles (Hassall's Corpuscles): Oval structures made up of round whorls of flattened epithelial reticular cells.
Tonsils
-
Structure: Masses of lymphoid nodules in pharynx:
- Palatine tonsils
- Lingual tonsils
- Pharyngeal tonsils (adenoids)
- Palatine and Lingual Tonsils: Covered with Stratified squamous nonkeratinized epithelium containing crypts.
- Pharyngeal Tonsils: Covered by ciliated pseudostratified columnar epithelium, lacking crypts.
- Cellular Composition: All tonsillar epithelia have intraepithelial lymphocytes and dendritic cells.
- Additional Palatine Tonsil Features: The tonsils are invaginated by deep grooves called tonsillar crypts, and lymphoid tissue below the epithelium contains lymphocytes and secondary lymphoid nodules.
- Additional Lingual Tonsil Features: Stratified squamous epithelium and crypts; similar lymphoid tissue makeup to palatine tonsils.
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Description
Explore the intricate microscopic structures of lymphatic organs including lymph nodes, spleen, thymus, and tonsils. This quiz will test your understanding of the location and cellular components involved in the lymphatic system.
