LYMPHOID TISSUE IV

Histology 2016-2017
Department of Anatomy &Histology: Dr.Rajaa Ali
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LYMPHOID TISSUE IV
SPLEEN
GENERAL FEATURES
• Spleen is the largest lymphoid organ present in the upper left part of abdominal cavity behind the stomach and is completely covered by peritoneum.
• Normally it is a blood-forming organ in foetal life and blood-destroying organ in postnatal life (graveyard of RBCs). Since it is in the bloodstream, it fi lters the blood from blood-borne antigens and microorganisms.

COMPONENTS/STRUCTURE (BOX 7.3)
A. Connective tissue framework
1. Capsule
2. Trabeculae
3. Reticular stroma (fi bres)
B. Parenchyma
1. White pulp (typical lymphoid tissue)
2. Red pulp (atypical lymphoid tissue)

Connective Tissue Framework
Capsule
• Covers the spleen completely.
• Lies deep to the mesothelial covering (peritoneum).
• Is formed by dense collagenous connective tissue and few smooth muscle fi bres. The smooth muscle fi bres are more in some mammals. Contraction of these muscles cause pumping of blood from the spleen into the circulation. Spleen acts as a reservoir of blood.