Functions of WBC::
They are the first line of defence against invasion by microbes foremost amongst them are the polymorphs and the monocytes these cells are motile and throw pseuodopodia to engulf the bacteria the process is called phagocytosis the other foreign bodies are also entrapped by them such as a splinter or thorn here they act as scavengers
The eosinophils and basophils are non motile and non phagocytic they are increased in number in asthma tropical eosinophilia worm infection etc iudicate some allergic condition
The lymphocytes are not motile have no proteolytic ferment and thus devoid of phagocytosis yet they are always found surrounding chronically inflamed tissues exhibiting small infiltration researches show they get destroyed liberating gammaglobulin an important source for antibody formation the corticosteroids are lymphopenic and inhibit the immune reactions
Natural killer cells:
They are type of lymphocytes which are large and granular but are small in number they circulate in blood and lymph and can lyse and kill cancer cells and virus infected body cells before immune system is activated they are non specific in their killing activity
Origin of leucocytes:
Red bone marrow gives birth to granulocytes the large and small lymphocytes are formed from the lymphoid tissue nodes which prevade in different parts of the body
the monocytes and transitional originate from the RES the granulocytes originate in the red bone marrow in the beginning they are non granular and are known as Myeloblasts in the second stage granules appear and the cells are called Myelocytes in the third stage the nucleus gets constricted at one point but lobulation do not occur the lobulation occurs in the fourth stage during circulation their life span is 3weeks
Lymphocytes originate in the lymphatic glands lymph tissues and spleen which abode the lymphoid tissue
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