In fact, about a third of a red blood cell is dedicated to hemoglobin alone, so no room remains for a nucleus or many of the structures that other cells have.
But wait! Blood cells does not contain nucleus, although they have nucleus at primary stage but as the haemoglobin produce in blood cell, it shrink nucleus which finally get disapper. Red blood cells, or erythrocytes ( erythro being Greek for 'red' and cyte meaning 'cells') are actually anucleated cells, meaning that they don't have a nucleus. Red blood cells have no nucleus, because most of their bulk is made up of hemoglobin, a compound that carries gases, such as oxygen and carbon dioxide. White blood cells, on the other hand, are actively working to help protect the body from infections and they need to be able to make proteins to do this, and therefore must keep their nuclei. They just carry chemicals around. Like mature red blood cells, in mammals reticulocytes do not have a cell nucleus. The nucleus is actually the control center of a cell. All other types of blood cells have nucleus. They are called reticulocytes because of a reticular (mesh-like) network of ribosomal RNA that becomes visible under a microscope with certain stains such as … A RBC has haemoglobin in it which carries oxygen. However, the function of RBCs is very simple. Don't go away just yet because this is actually a much more tricky question than you would expect.

It has DNA in it which is required for reproduction of any cell. Mature red blood cells do not need to have a nucleus because they have already made all the proteins they will ever need. Red blood cells are the only cells in the human body that do not have a nucleus. Red blood cells do not have a nucleus while cheek cells have a nucleus.