What accumulates in lymph nodes during an active viral infection? Identify the best description of the contents and structures present.

Introduction:
Lymph nodes are hubs for immune surveillance and response. During infections like the common cold, nodes enlarge due to cellular recruitment and proliferation, while lymph-borne antigens and pathogens are filtered and retained.

Given Data / Assumptions:

• Nodes receive afferent lymph containing antigens, pathogens, and dendritic cells.
• Germinal centers form with proliferating B cells and helper T cells.
• Anatomical lymphatic vessels enter and exit nodes.

Concept / Approach:

All listed features coexist during active responses: abundant leukocytes, trapped antigens/pathogens, and the lymphatic conduits that shuttle lymph through the node’s architecture.

Step-by-Step Solution:

Verification / Alternative check:

Histology and imaging show increased cellularity, antigen deposition on follicular dendritic cells, and well-defined lymphatic vessels during infections.

Why Other Options Are Wrong:

Options A, B, C each capture part of the truth but are incomplete alone.

Option E: Red blood cells are not typical residents; nodes are lymphoid, not hematologic filtration organs like the spleen.

Common Pitfalls:

Confusing lymph nodes with spleen (blood-borne antigen) or assuming nodes only contain fluid without significant cellular dynamics.

Final Answer:

All of the above