General Characters of RBCs:
Shape: RBCs are rounded biconcave non-nucleated discs.
Size: The diameter of RBCs varies between 6-9um.
Colour: RBCs are greenish or orange-yellow. But when they condense the colour is red.
Number: In males, the number varies between 5 & 5.5 millions per cubic mm. In females, it is 4.5-5 millions/cu mm.
Structure (EM): RBCs are not true cells. They have no nuclei or cytoplasmic organelles. Their cytoplasm contains only Haemoglobin (Hb). They are surrounded by highly flexible plasma membrane.
Function: RBCs transport oxygen from the lung to tissues &transport carbon dioxide from tissues to the lung.