Spleen Histology & Microcirculation AL

Spleen Histology & Microcirculation

Spleen Histology & Microcirculation (Animated Video)

 

Spleen (secondary lymphoid organ) is the main site of Blood Filtration.

Spleen is called a haemo-lymph organ beacuse in fetal life, it help in formation of blood (produces RBC), and after birth it Begin to manufacture lymphocytes.

Site of formation of RBC in fetal life

site of formation of RBC in fetal life


Histology of Spleen:

Spleen is composed of Capsule & Parenchyma. Capsule extended down to form the trabeculae, which give it lobular appearance.
Whereas Parenchyma has two components.

  1. White Pulp
  2. Red Pulp

T & B lymphocytes aggregated around the central arterioles; (which branched from trabecular artery) forms the White Pulp.


Arrangement of lymphoid tissue in White Pulp:

1. T-cells around the central arteriole.
2. B-cells is arranged in the middle of white pulp with germinal center, where germinal centre is observed as lightly stained area over histological slide.
3. Dendritic antigen-presenting cells around the periphery.

 

Red Pulp



Red Pulp contain:

1. Venous Sinusoids (Fenestrated porous capillary bulb)
2. Splenic cord is mainly composed  of reticular fibers & cells (which is the framework of lymphoid tissues), macrophages, Blood (i.e. RBC & other leukocytes).


Red Pulp is like a open space cavity filled with blood.
In Splenic cord macrophages are present which phagocytose the damaged, expired, RBC(erythrocyte).
So, the chief & important function of Spleen is to filter out the blood & scavenger of RBC(erythrocytes).


Main Function of Spleen:

1. Filter blood by removing worn-out RBC & micro agents - (which occur around Red Pulp).
2. Produce new lymphocytes which is later transported through blood-stream to target site - (Production occur around White Pulp).

 

Simple Concept:

If any antigen/pathogens are present then, White Pulp begins to produce more & more lymphocytes as a defense mechanism.

 

Microcirculation in Spleen:

1. Open/Slow Circulation:
Central arteriole Penicillar artery → Open space around red pulp Venous sinusoid Trabecular Vein Splenic vein 
2. Closed/Fast Circulation:
Central arteriole Penicillar artery Venous Sinusoid Trabecular vein → Splenic vein


Conclusion:

Microstructure of Red Pulp makes the filtration of Blood possible.