Reticulocyte

Immediate and a bit larger preliminary stage of a erythrocyte. An increase in the reticulocyte count indicates massive erythrocyte formation (e.g. after blood loss such as nosebleeds or haemolysis).

https://flexikon.doccheck.com/de/Retikulozyt
https://de.wikipedia.org/wiki/Erythropoese#Retikulozyt