4. Lymphoid Tissue Flashcards
What is the definition of secondary lymphoid tissue?
Tissue where lymphocytes are activated in response to antigens.
(Tonsils, lymph nodes, spleen, MALT in small intestine etc.)
Where would you find diffuse lymphoid tissue?
Lamina propria of the GI
Genitourinary tract (especially in females)
Respiratory passages
How could one identify a lymphatic nodule?
You would have a clear accumulation of lymphocytes in a dark staining nodule without a connective tissue border.
What is a primary lymphatic nodule?
A nodule full of inactive or nieve lymphocytes
Does not have a germinal center
What do we call the darker staining region around the germinal center of a lympatic nodule?
Mantle zone or corona
Where would you find aggregated lymphoid tissue?
Tonsils
Peyer’s patches
Veriform appendix
Mucosa-associated lymphatic tissue (MALT)
What area of aggregated lymphatic nodules can be partially encapsulated?
Tonsils
What lines the palantine and lingual tonsils?
Nonkeratinized stratified squamous epithelium
What are the invaginations of the palantine tonsil called?
Tonsillar crypts
What lines the pharyngeal tonsil?
Pseudostratified columnar ciliated epithelium
Which pharyngeal tonsil has a complete, but thin, capsule?
Pharyngeal tonsil
Where are Peyer’s patches found?
What covers them?
In the ileum associated with intestinal villi
Simple columnar epithelium with goblet cells
What covers the lymphatic nodules of the veriform appendix?
What differentiates it from peyer’s patches?
Simple columnar epithelium
The covering epithelium has crypts, but no villi
What is MALT?
How is it categorized?
Mucosa-Associated Lymphoid Tissue
It is categorized by the associated tissues, eg: GALT for GI-Associated Lymphoid Tissue
What sort of connective tissue composes lymph nodes?
Reticular tissue
What is the parenchyma of a lymph node?
The cortex and medulla - everything that isn’t the supporting connective tissue on the outside
What is the stroma of a lymph node?
The supporting connective tissue on the outside.
What is the hilum of a lymph node?
Exit for efferent lymph
Entry / exit for neurovasculature
What part of the lymph node receives lymph from afferent lymphatic vessels?
The superficial cortex
What happens at the medulla of a lymph node?
Sinuses come together at the efferent lymphatic vessel