reticulocyte
Concise Oxford English Dictionary © 2008 Oxford University Press:
reticulocyte /rɪˈtɪkjʊlə(ʊ)sʌɪt/
▶noun Physiology an immature red blood cell without a nucleus, having a granular or reticulated appearance when suitably stained.
'reticulocyte' also found in these Oxford entries:

