ERYTHROCYTES

Erythrocytes or red blood cells (RBC) are the most abundant of all the cells in blood. A healthy man has on an average 5 million to 5.5 million of RBCs mm-3 of blood. They have red coloured iron containing complex protein called heamoglobin. The molecule play a significant role in transport of respiratory gases. RBCs are formed in red bone marrow in adult/ mammals. In foetus RBCs are formed mainly in liver. RBCs of camel is oval. RBCs of frog is nucleated, oval and biconvex. RBCs are devoid of nucleus and biconcave in shape in most of the mammals. Mammalian RBCs lack mitochondria, golgibody, ER and lysosome. Mammalian RBCs loose their nuclei during reticulocyte stage of their development.

RBCs have an average life span of 120 days after which they are destroyed in the spleen (graveyard of RBCs). Mammalian RBCs have short life span due to absence of nucleus. 

Formation of blood cells is called heamopoiesis. 

Formation of RBCs is called erythropoiesis.