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A proerythroblast (or rubriblast, or pronormoblast) is the earliest of four stages in development of the normoblast.
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
- Histology image: 01804loa – Histology Learning System at Boston University - "Bone Marrow and Hemopoiesis: bone marrow smear, erythroblast series with proerythroblast"
- Histology at KUMC blood-blood04
- Image and description at purdue.edu
- Histology of "promegaloblast" at marist.edu (pernicious anemia)
- Interactive image at usuarios.lycos.es
- Overview at temple.edu
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Template:SIB cs:Proerytroblast id:Rubriblas sk:Proerytroblast