Proerythroblast

Overview
A proerythroblast (or rubriblast, or pronormoblast) is the earliest of four stages in development of the normoblast.

Laboratory findings
In histology, it is very difficult to distinguish it from the other "blast" cells (lymphoblast, myeloblast, monoblast, and megakaryoblast.) The cytoplasm is blue in an H&E stain, indicating that it is basophilic.

"Pronormoblast" vs. "proerythroblast"
Some sources consider the terms "pronormoblast" and "proerythroblast" to be synonyms. However, other sources consider "proerythroblast" to be a parent term, divided into the following two categories:


 * "pronormoblast" - normal develoment
 * "promegaloblast" - abnormal development