Question

What happen if our red blood cell have nucleus?

Answer 1

well before maturing they bear nucleous i m just giving a guess dat it will divide and elongate more but now problem will occur as blood vessel will be unable to carry blood cells..

Answer 2

Then likely you have what are called nRBCs or nucleated red blood cells. These can be indicative of pathology if there are too many of them. Differential diagnoses include regenerative anemia, bone marrow injury, neoplasias, splenic injury (or no spleen).