Histology for PathologyLymphoid Organs

Theresa Kristopaitis, MDAssociate Professor

Director of Mechanisms of Human Disease

Kelli A. Hutchens, MD, FCAPAssistant Professor

Assistant Director of Mechanisms of Human Disease

Loyola Stritch School of Medicine

Lymphoid OrgansLymph Nodes, Spleen, Thymus

• List the main function(s) of lymph nodes.• On an H&E stained section of a lymph node identify the capsule,

subcapsular sinus, cortex, and medulla.• Identify the germinal center of a secondary lymphoid follicle. • Outline the path of lymph through a lymph node.• On an H&E stained slide of the spleen, identify the capsule, white pulp

(central artery, nodule) and red pulp.• Summarize the key functions of the white pulp and red pulp of the spleen. • On an H&E stained section of an infant/child thymus identify the cortex

and medulla of thymic lobules. • Define “Hassal corpuscle” and identify on a histologic section. • Summarize the key function(s) of the thymus. • Define “Mucosa-Associated Lymphatic Tissues” and list in which organs

they are found.

Lymph Node

CapsuleCortex

MEDULLA

Lymph node

Subcapsular Sinus

Lymph Node Follicle with Germinal Center (Secondary Follicle)

Pale medullary sinuses surrounding darker medullary cords. You can see many stellate reticular cells which, with reticular fibers, make a meshwork through the sinuses. Lymph "percolates" through the meshes of the sinuses while debris of foreign matter in it is phagocytized.

Spleen

Red pulp White pulp

SpleenWhite pulpRed pulp

White PulpCentral arteryLymphoid nodule

Spleen Red Pulp

Red pulp consists of open sinuses and cellular cords

ThymusInfant

Medulla

cortex

Thymus Medulla

Hassall’s Corpuscle

Adult Thymus

Panoramic view of adult thymus, largely replaced with adipose tissue. There are recognizable remnants of thymic lymphatic tissue, however,and Hassall's corpuscles are still present in the medulla.

Mucosa Associated Lymphoid Tissue

Stomach