Are microproerythroblasts in human bone marrow real or artefacts? A cytochemical note
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Updated: Aug 16, 2026
A Three-dimensional Tissue Culture Model to Study Primary Human Bone Marrow and its Malignancies
Published on: March 8, 2014
Karel Smetana1, Ilona Jirásková, Hana Klamová
1Clinical Department, Institute of Haematology and Blood Transfusion, U nemocnice 1, Prague 2, 128 20 Czech Republic. karel.smetana@ukht.cz
Abstract:
Early erythroid precursors were studied in human bone marrow smears to provide more information on small proerythroblasts--"microproerythroblasts"--using a silver reaction to demonstrate silver stained nucleolar organizer regions (AgNORs) and light microscopic densitometry of large irregularly shaped nucleoli and cytoplasm stained for RNA. No significant differences were found for the density of such nucleoli and basophilic cytoplasm between characteristic large proerythroblasts with a nuclear diameter larger that 9 microm (K2 and K1 erythroblasts) and small proerythroblasts--"microproerythroblasts" representing a subpopulation of K1/2 erythroblasts (early basophilic erythroblasts), which are characterized by a smaller nuclear diameter. In addition, large irregularly shaped nucleoli of "microproerythroblasts" possessed numerous silver stained particles representing AgNORs similar to those of large proerythroblasts. The number of AgNORs in "microproerythroblasts" was slightly, but significantly, smaller than that in large characteristic proerythroblasts.
Insights
This study investigated microproerythroblasts, finding no significant density differences in nucleoli or cytoplasm compared to larger proerythroblasts. However, microproerythroblasts showed a slightly lower number of silver-stained nucleolar organizer regions (AgNORs).
Area of Science:
- Hematology
- Cell Biology
- Histology
Background:
- Erythropoiesis involves sequential maturation of erythroid precursors.
- Distinguishing early erythroid cell subtypes is crucial for understanding normal and abnormal hematopoiesis.
- Microproerythroblasts represent a less-characterized subpopulation of early erythroid cells.
Purpose of the Study:
- To characterize microproerythroblasts, a subpopulation of early erythroid precursors.
- To compare microproerythroblasts with characteristic large proerythroblasts using cytochemical and densitometric methods.
- To investigate the presence and density of silver-stained nucleolar organizer regions (AgNORs) in microproerythroblasts.
Main Methods:
- Analysis of human bone marrow smears.
- Silver staining technique to visualize AgNORs.
- Light microscopic densitometry for nucleoli and RNA-stained cytoplasm.
Main Results:
- No significant differences in nucleolar or cytoplasmic RNA density between microproerythroblasts and large proerythroblasts (K1/K2 erythroblasts).
- Microproerythroblasts exhibit large, irregularly shaped nucleoli with numerous AgNORs, similar to large proerythroblasts.
- A statistically significant, though slight, reduction in the number of AgNORs was observed in microproerythroblasts compared to large proerythroblasts.
Conclusions:
- Microproerythroblasts share key cytochemical and nucleolar characteristics with larger proerythroblasts.
- The slightly lower AgNOR count in microproerythroblasts may indicate subtle differences in proliferative activity or nucleolar function.
- These findings contribute to a more detailed understanding of early erythroid cell differentiation.
