1) HEMOPOIESIS  (=HP.).         2) IMMUNE SYSTEM.
           HP before birth –  is    PREnatal     HP.           HP  after  birth  –  is   POSTnatal   HP.
 PREnatal HP includes 4 phases:   1) MESOBLASTIC phase (in   yolk SAC   mesoderm),   
          2) HEPATIC phase,     3) Splenic  phase,     4)Myeloid  phase   (in  red bone marrow).
 1) MESOBLASTIC phase:  MESOderm/mesenchyme of YOLK SAC –    is   earliest  
place of development of  first blood vessels  and    first  blood CELLS, named MEGALOblasts –
 it are  primary,   BIG-sized,   NUCLEATED   erythrocytes  (or red blood cells, or  RBCs).
 2) HP in EMBRYIONIC liver—is HEPATIC phase. Liver  produces nucleated and enucleated RBCs  
   and leukocytes.                 After birth   HP   in liver   happens   NEVER.
                                                               POSTnatal  HP: 
 RED BONE MARROW is UNIVERSAL  hemopoietic organ.       ONLY it   produces:  
       1)RBCs,   2) All Granulocytes,     3)Monocytes,      4)Platelets,   5)Naïve B-lymphocytes.  
   BUT,  T-lymphocytes are  formed  in:    THYMUS,      SPLEEN,     LYMPH NODES.
  ALL blood cells/formed elements are developed from  common  most  IMMATURE  cell,
         named    “Pluripotential   Hemopoietic   Stem   Cell”   ( =  PHSC) .
  ERYTHROpoiesis (=EP) –  is development of  RBCs.  Shortened differon  of cells inside EP is:
 1)PHSC- 2)Erythroblasts, including NORMOBLASTs-3)RETICULOCYTE-4)ERYTHROCYTE.
   Each following cell is developed from  previous. Nucleus EXTRUSION happens in   normoblast.   Thus,    reticulocyte  and  erythrocyte   DON’T have nuclei.   Erythroblasts   in bone marrow  
   attaché to long cytoplasmic processes of MACROPHAGE,  forming  ERYTHROBLASTIC
         ISLETS.    Macrophage supplies erythroblasts by IRON-containing protein f e r r i t i n.
 THROMBOCYTOpoiesis.(=TP) –  is development of  platelets (thrombocytes). Shortened differon  
  of cells inside TP is: )PHSC-  2)Megakaryoblast-   3) MEGAKARYOcyte-    4)Platelet. MEGAKARYOCYTE –is LARGE  POLYPLOID cell (64n-128n chromosomes), surrounding SINUSOIDAL capillary of red bone marrow. It protrudes cytoplasmic processes into capillary lumen. Then small fragments of cytoplasm are pinched-off into lumen and become   platelets.
 MONOCYTOpoiesis (=MP) -  is development of  monocytes/ tissue MACROPHAGES. Shortened differon  of cells inside MP is:1)PHSC- 2)Monoblast- 3) MONOCYTE-  4) Tissue  MACROPHAGE.
 Monocytes circulate in bloodstream 1-2days, then EXIT into surrounding loose CONNECTIVE tissue and differentiate into definitive cells-  tissue  MACROPHAGES.
 GRANULOCYTOpoiesis (=GP) -  is development of granulocytes. Shortened differon  of cells inside GP is: 1)PHSC- 2)MYELOBLAST-3)YOUNG granulocyte(metamyelocyte)-4)STAB (or BAND) form-5)MULTILOBED (mature) granulocyte. During maturation cells change shape of it nucleus from spherical to multilobed and accumulate   SPECIFIC GRANULES  in it cytoplasm.
 LYMPHOCYTOpoiesis(=LP)- –  is development of  T- and B-lymphocytes. LP happens in 2 organs  
 and includes 2 types of differentiation.  Red bone marrow produces NAÏVE mature B-lymphocytes.  
  It is   antigenINDEPENDENT   differentiation of  B-cells.
  THYMUS produces NAÏVE mature T-helpers and T-killers.   It is   antigenINDEPENDENT  differentiation of T-cells. In spleen and lymph nodes naïve B-cells differentiate into PLASMA cellss.
  It is   antigenDEPENDENT    differentiation of B-cells. In spleen and lymph nodes naïve T-helper  
   cells differentiate into T-helper  fist type and T-helper  second type. Also activation of real T-killer  
 cells  happens..  It is antigenDEPENDENT    differentiation of  T-cells.
                 IMMUNE SYSTEM. – is group of  immune cells,   capable   SELECTIVLY
to recognize and eliminate most dangerous antigens: CANCER cells and virus-INFECTED cells.
 Immune proteins, named IMMUNOGLOBULINS (=IGs; =antibodies) facilitate eliminination of antigens. Thus,  IGs-producing cells (PLASMA cells)  also belong to immune system.
 MAIN types of immunocytes: 1) T-KILLER cells (or T-CYTOTOXIC lymphocytes). Funct.: It destroy 3 main  targets (foreign antiGENS):   1)CANCER cell;     2)Virus-INFECTED cell;  
         3)Transplanted organ (or GRAFT), promoting   rejection (casting-off) of  it.
 2) T-helper  1^st type. It secretes interleukin-2 (IL-2) and activates function of T-CYTOTOXIC lymphocyte. 3)T-helper 2^nd type.  It secretes IL-3, IL-4 and activates differentiation of naïve B-lymphocyte in PLASMA cell. Funct.: PLASMA cell secretes 5 classes of IMMUNOGLOBULINS:
(or antibodies):   Ig A, Ig D.   Ig E,  Ig G,   Ig M.