LYMPH NODE AND SPLEEN LYMPH NODE Small bean

LYMPH NODE AND SPLEEN.

LYMPH NODE • Small bean shaped structures • Found at junctions of lymphatic networks. • Covered by a fibrous capsule. • Has a subcapsular sinus connected to subtrabecular, and medullary sinus • Afferent lymph vessels open into subcapsular sinus • Efferent lymphatics leave the hilus. • Has outer cortex and inner medulla.

• FUNCTIONS OF LYMPH NODE 1)Filters the lymph and macrophages carry out phagocytosis. 2)Concentration on antigens and their presentation to the lymphocytes. 3)Cell mediated and humoral immunity. 4)Memory cells-more rapid response to antigen when it is next encountered.

• • LYMPHATIC CIRCULATION-

MICROSCOPIC FEATURES • Covered by capsule which sends in trabeculae. • Outer CORTEX has rounded lymphoid nodules made up of lymphocytes PRIMARY NODULE • Some nodules show GERMINAL CENTRES SECONDARY NODULE • Inner MEDULLA contains lymphocytes arranged in cords called medullary cords between medullary sinuses.

Lymph node (Panoramic view)

Microscopic veiw

Vascular friable organ SPLEEN Capsule thick & trabeculae thick. Parenchyma divided into white pulp& red pulp. White pulp is lymphatic nodule with eccentric arteriole. Red pulp contains blood sinuses with RBC. In between blood sinuses and rbc, lymphocytes are arranged in cords called Billroth cords.

Microscopic veiw

SPLENIC CIRCULATION • OPEN CIRCULATION • CLOSED CIRCULATION

• OPEN CIRCULATION • The capillaries end by opening into the red pulp from where the blood enters the sinusoids through their walls.

• CLOSED CIRCULATION • The capillaries are continuous with the venous sinusoids in the red pulp and sinusoids join together to form splenic veins.

LYMPH NODE & SPLEEN (main features) LYMPH NODE SPLEEN • Capsule & subcapsular sinus. • Thick capsule & trabeculae. • Cortex with lymphatic nodules with germinal centres. • White pulp & red pulp. • Medulla with cords &sinuses. • White pulp contains eccentric arteriole.

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