Spleen

 

  


Spleen explanatory video

The spleen is covered by two coats.   The outer most is the serous coat which is derived from the peritoneum.   The inner coat is called the capsule of the spleen.   This capsule is fibromuscular consisting of collagenous fibers and smooth muscle.   From the inner coat of the trabeculated structures.   The trabecula are made up of collagenous fibers and smooth muscles.   When the capsule and the trabeculae contract, they release blood from inside the spleen into the circulation.   Beneath the trabeculae are reticular spaces called reticulum.   The reticulum consists of macrophages, collagenous fibres and elastic fibres.

Microcirculation of the spleen.

The spleen is supplied by the splenic artery and drained by the splenic vein.   The artery divides into five arterioles as it enters into the splenic mass. The arterioles enter the splenic substance to form red pulp, accompanied by areas of many white cells, predominantly lymphocytes called white pulp. Both are now called splenic pulp.

 

Red pulp White pulp

Splenic pulp

The entire splenic substance is divided into two pulps depending on their gross morphological appearance after cross section, white pulp and red pulp. The two together represents the splenic pulp.

White pulp

The arterioles are covered for a short distance as they enter the splenic mass by intima which become later replaced by lymphatic follicles. The follicles form a body around the arterioles called the  Malphigian body and they appear white under the microscope, hence the name white pulp. Each Malpighian body also called lymphatic nodule has a germinal center with surrounding packed lymphocytes. Each also has one or more  arteriole(s) in each node placed eccentrically. The lymphocytes surrounding the Malpighian bodies are B lymphocytes while the remaining lymphocytes of the white pulp are mainly T lymphocytes.

The communication between the ellipsoid and sinusoids are described in three theories- closed, open and combination of the two.

 

 

 

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Creator: Oluwole Ogunranti

 
                   
 

 

 

 

 

 

 

 

 

 

Microcirculation in the spleen

 

 

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