Lymphatic System Histology Overview

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Questions and Answers

What is the main function of the lymph nodes?

Defense against microorganisms and tumor cells (correct)

Storage of platelets

Production of red blood cells

Filtration of blood

What type of cells are predominantly found in lymph nodes?

Neutrophils

Plasma cells (correct)

Basophils

Eosinophils

Which region of a lymph node is characterized by a lack of lymphoid nodules?

Medulla

Subcapsular sinus

Outer cortex

Paracortex (correct)

Where do T lymphocytes mature after originating in the red bone marrow?

Thymus Signup and view all the answers

Which structure ensures that lymph flow is unidirectional in lymph nodes?

Valves in the lymphatics Signup and view all the answers

The spleen plays a crucial role in the destruction of which type of cells?

Old erythrocytes Signup and view all the answers

What happens to the thymus after puberty?

It undergoes involution and decreases in size Signup and view all the answers

Which cells are found in the cortical region of the thymus?

Thymocytes and macrophages Signup and view all the answers

What component of the spleen is responsible for filtering blood?

Splenic pulp Signup and view all the answers

What is located at the hilum of a lymph node?

Efferent lymphatic vessel and blood vessels Signup and view all the answers

What do Thymic Epithelial Cells (TECs) contribute to in the thymus?

Promotion of T cell maturation Signup and view all the answers

Which of the following is NOT a major anatomical region of the lymph node?

Parathyroid region Signup and view all the answers

What characterizes the staining appearance of the thymic cortex compared to the medulla?

It is darkly basophilic and denser in lymphocytes Signup and view all the answers

What structures are unique to the thymic medulla?

Hassall corpuscles Signup and view all the answers

What is the function of the connective tissue capsule in the thymus?

Separate lobules within the thymus Signup and view all the answers

What is the primary lymphoid organ responsible for the maturation of B lymphocytes?

Bone marrow Signup and view all the answers

What is the main function of mucosa-associated lymphoid tissue (MALT)?

To protect against pathogens invading the mucosa Signup and view all the answers

Which of the following correctly identifies the types of tonsils present in the mucosa?

Palatine, lingual, and pharyngeal tonsils Signup and view all the answers

Which type of epithelium covers the pharyngeal tonsil?

Pseudostratified ciliated columnar epithelium Signup and view all the answers

Where are Peyer's patches predominantly located?

In the ileum Signup and view all the answers

What percentage of the body’s immune cells is found in MALT?

Up to 70% Signup and view all the answers

What distinguishes lymph nodes from MALT in structure?

Lymph nodes are encapsulated structures Signup and view all the answers

Where in the body is the concentration of lymph nodes typically highest?

In the axillae and groin Signup and view all the answers

What type of connective tissue is associated with MALT?

Loose connective tissue Signup and view all the answers

Study Notes

Lymphatic System Histology

All lymphocytes (T & B cells) originate in red bone marrow, but mature in primary lymphoid organs.
B cells remain and mature in the bone marrow.
T cells migrate from the bone marrow to the thymus.
After maturation, B and T cells circulate to secondary lymphoid organs (e.g., MALT, lymph nodes, spleen).
Stem cells in the red bone marrow differentiate into undifferentiated lymphocytes.
Some undifferentiated lymphocytes are processed in the thymus to become T cells.
Other undifferentiated lymphocytes mature into B cells, possibly in the bone marrow.
T and B cells travel through the bloodstream to lymphoid organs.

Thymus

The thymus is a primary lymphoid organ in the mediastinum.
It's bilobed and highly active until puberty, after which it shrinks.
The thymus has connective tissue septa that divide it into lobules.
The cortex, stained darkly basophilic, has a high density of lymphocytes.
The medulla, stained lightly, has fewer lymphocytes and Hassall corpuscles (aggregates of thymic epithelial cells).
Thymic epithelial cells (TECs) are involved in T cell development.
TECs are involved in the maturation of T cells.

Mucosa-Associated Lymphoid Tissue (MALT)

MALT is widespread in mucosal linings of digestive, respiratory, and genitourinary tracts.
MALT protects against pathogens with collections of lymphocytes, plasma cells, and lymphoid nodules.
MALT includes large aggregates of lymphoid tissue like tonsils, Peyer's patches in the ileum, and the appendix.
MALT may contain up to 70% of the body's immune cells.
Tonsils are lymphoid masses located in the oral cavity and nasopharynx.
Peyer's patches are lymphoid tissue aggregations in the ileum.
The appendix is a lymphoid-rich structure that projects from the cecum.

Lymph Nodes

Lymph nodes are bean-shaped structures found throughout the body.
Lymph nodes act as filters for lymph, preventing the spread of microorganisms and tumor cells.
They contain lymphocytes, plasma cells, and macrophages.
Lymph nodes have a capsule, cortex, medulla, and paracortex.
Lymph enters through afferent lymphatics and exits through efferent lymphatics.

Spleen

The spleen is a large accumulation of lymphoid tissue in the body, also a vital filter for blood.
The spleen is involved in filtering blood and removing old red blood cells.
It contains white pulp (lymphoid nodules and periarterial lymphoid sheaths), and red pulp (sinusoids and cords).
The splenic artery branches penetrate the hilum (concave region) to reach the pulp
The white pulp contains lymphocytes and is involved in immune responses to blood-borne antigens.
The red pulp filters blood and removes old red blood cells.

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Description

This quiz focuses on the histology of the lymphatic system, including the development and maturation of lymphocytes in primary and secondary lymphoid organs. It covers key features of the thymus and its role in T cell maturation. Test your knowledge on these essential concepts in immunology.