The Composition of immune Cells in Head Kidney of Grass Carp (Ctenopharyngodon idellus) Together With Ontogenic Change of Their Numbers

Under light and electron microscope,the head kidney of grass carp was found to have two type of veins:head-renal and portal veins,and a number of sinusoids with extensive lumina.The lymphocytes of head kidney were distributed around portal veins and its sinusoids,forming lymphocyte aggregate region,while granulocytes distributed around head-renal veins and its sinusoids,forming granulocyte aggregate region.The head kidney contained a number of immune cells,comprised approximately 62.2% lymphocyte,36.6% granulocytes,1.2% monocytes and macrophages.The weight of head kidney organ and amounts of its immune cells were examined for each grow stage of grass carp.It was shown that total weight of head kidney increased with body weight and age.However,The development of the head kidney correlates better with weight than with age.Total number of immune cells of head kidney increased correspondingly with head kidney weight.In general,the number/mg weight of head kidney stabilized from 100 to 132 ten thousand,the mean was 117.3(±9.98)ten thousand.