1. Lab 35A
Lymphoid Tissues

2. Slides
Peyer’s Patches: Label the lumen of the digestive tract, digestive tissue, and lymphoid tissue.
Lymph Node: Label: capsule, subcapsular space, nodules within the lymph node, germinal centers, the hilus region, and any visible blood vessels. Using a higher power objective, examine (look at, but don’t draw) a germinal center.

3. Nodules

4. Lymph Node - Structure
Trabeculae: fibrous partitions made of collagen fibers that extend from capsule into interior of lymph node
Hilus: shallow indentation where blood vessels and nerves reach the lymph node
Afferent Lymphatic Vessels: carry lymph from peripheral tissues to lymph node
Efferent Lymphatic Vessels: leave lymph node at hilus, carry lymph to venous circulation

5. Lymph Flow
Flows from afferent lymphatics through lymph node in a network of sinuses:
From subcapsular sinus:
contains macrophages and dendritic cells
Through outer cortex:
contains B cells within germinal centers
Through deep cortex:
dominated by T cells
Through the core (medulla):
contains B cells and plasma cells
organized into medullary cords
Into hilus and efferent lymphatics

6. Lymph Node

7. Slides
Spleen: Draw and clearly label: splenic nodules, white pulp, and red pulp. Can you find a central artery?
Thymus: Use low power, label: septa, medulla, cortex, and any blood vessels.
Which region of the thymus is primarily composed of epithelial cells? What hormone do these epithelial cells make and release? What is believed to be the function of this hormone?

10. Spleen

11. Thymus