Lymph node cortex vs Lymph node medulla
How to tell Lymph node cortex and Lymph node medulla apart when a board question makes them look alike.
Cortex is B-cell follicles/germinal centers; medulla is cords and sinuses with plasma cells/macrophages.
Side by side
Lymph node cortex contains B-cell follicles, germinal centers, and antigen-driven B-cell proliferation.
Lymph node medulla contains medullary cords with plasma cells/macrophages and sinuses that filter lymph exiting the node.
Lymph node cortex contains B-cell follicles, germinal centers, and antigen-driven B-cell proliferation.
Lymph node medulla contains medullary cords with plasma cells/macrophages and sinuses that filter lymph exiting the node.
The repair move
Before naming the answer, force the stem through the separator: Cortex is B-cell follicles/germinal centers; medulla is cords and sinuses with plasma cells/macrophages.
Try a free question
CoreA histology slide of a lymph node shows distinct B-cell follicles with germinal centers in the outer region. Within these germinal centers, B cells are undergoing somatic hypermutation and class switching after antigen exposure. Which region of the lymph node is this?
Show answer and explanation
Answer: A. Lymph node CORTEX. Lymph node CORTEX is the outer region containing B-cell follicles. Primary follicles (before antigen exposure) contain naive B cells; secondary follicles develop germinal centers after activation, where B cells undergo somatic hypermutation and class switching with help from follicular helper T cells (Tfh). High endothelial venules in the paracortex (deep cortex) allow lymphocyte entry.
Why the other choices are tempting
- B. Paracortex is the deep cortex with T cells and high endothelial venules; DiGeorge syndrome causes paracortical depletion.
- C. Medullary cords contain plasma cells and macrophages.
- D. Medullary sinuses filter lymph before it exits through the efferent lymphatic.
- E. Subcapsular sinus is where afferent lymph first enters the node.
Flashcards
Tap a card to flip it.
What clue supports Lymph node cortex?
Choose Lymph node cortex when the stem gives this pattern: Lymph node cortex contains B-cell follicles, germinal centers, and antigen-driven B-cell proliferation.
What clue supports Lymph node medulla?
Choose Lymph node medulla when the stem gives this contrasting pattern: Lymph node medulla contains medullary cords with plasma cells/macrophages and sinuses that filter lymph exiting the node.
Quick answers
What is the fastest way to tell Lymph node cortex from Lymph node medulla?
Cortex is B-cell follicles/germinal centers; medulla is cords and sinuses with plasma cells/macrophages.
What is the key clue for Lymph node cortex?
Lymph node cortex contains B-cell follicles, germinal centers, and antigen-driven B-cell proliferation.
What is the key clue for Lymph node medulla?
Lymph node medulla contains medullary cords with plasma cells/macrophages and sinuses that filter lymph exiting the node.