A proerythroblast (or rubriblast, or pronormoblast) is the earliest of four stages in

development Development or developing may refer to: Arts *Development hell, when a project is stuck in development *Filmmaking, development phase, including finance and budgeting *Development (music), the process thematic material is reshaped *Photographi ...

of the

normoblast A nucleated red blood cell (NRBC), also known by several other names, is a red blood cell that contains a cell nucleus. Almost all vertebrate organisms have hemoglobin-containing cells in their blood, and with the exception of mammals, all of the ...

. In

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...

, it is very difficult to distinguish it from the other "-blast" cells (

lymphoblast __NOTOC__ A lymphoblast is a modified naive lymphocyte with altered cell morphology. It occurs when the lymphocyte is activated by an antigen (from antigen-presenting cells) and increased in volume by nucleus and cytoplasm growth as well as new mRN ...

myeloblast The myeloblast is a unipotent stem cell which differentiates into the effectors of the granulocyte series. It is found in the bone marrow. Stimulation of myeloblasts by G-CSF and other cytokines triggers maturation, differentiation, proliferation ...

monoblast Monoblasts are the committed progenitor cells that differentiated from a committed macrophage or dendritic cell precursor (MDP) in the process of hematopoiesis. They are the first developmental stage in the monocyte series leading to a macrophage. ...

, and

megakaryoblast A megakaryoblast is a precursor cell to a promegakaryocyte, which in turn becomes a megakaryocyte during haematopoiesis. It is the beginning of the thrombocytic series. Development The megakaryoblast derives from a CFU-Meg colony unit of plurip ...

). The

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. Th ...

is blue in an

H&E stain Hematoxylin and eosin stain ( or haematoxylin and eosin stain or hematoxylin-eosin stain; often abbreviated as H&E stain or HE stain) is one of the principal tissue stains used in histology. It is the most widely used stain in medical diagn ...

, indicating that it is

basophilic Basophilic is a technical term used by pathologists. It describes the appearance of cells, tissues and cellular structures as seen through the microscope after a histological section has been stained with a basic dye. The most common such dye ...

. Proerythroblasts arise from the

CFU-e CFU-E stands for Colony Forming Unit-Erythroid. It arises from CFU-GEMM (via BFU-E, which stands for "erythroid burst-forming units") and gives rise to proerythroblasts. Murine CFU-E assay CFU-E is a stage of erythroid development between the ...

(colony-forming unit

erythroid Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

) cells, and give rise to basophilic

erythroblasts A nucleated red blood cell (NRBC), also known by several other names, is a red blood cell that contains a cell nucleus. Almost all vertebrate organisms have hemoglobin-containing cells in their blood, and with the exception of mammals, all of the ...

. In the

mouse A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...

, proerythroblasts are large committed progenitors that express high levels of

transferrin receptor Transferrin receptor (TfR) is a carrier protein for transferrin. It is needed for the import of iron into the cell and is regulated in response to intracellular iron concentration. It imports iron by internalizing the transferrin-iron complex thro ...

(iron acquisition receptor), the

erythropoietin receptor The erythropoietin receptor (EpoR) is a protein that in humans is encoded by the ''EPOR'' gene. EpoR is a 52kDa peptide with a single carbohydrate chain resulting in an approximately 56-57 kDa protein found on the surface of EPO responding cells. ...

(EpoR), some c-Kit (stem cell factor receptor), and are Ter119 (

cell surface molecule Cell adhesion molecules (CAMs) are a subset of cell surface proteins that are involved in the binding of cells with other cells or with the extracellular matrix (ECM), in a process called cell adhesion. In essence, CAMs help cells stick to each ...

)-positive. Their proliferative capacity is more limited compared to the preceding stage, the CFU-e. In vivo, starting with the proerythroblast stage, erythroid cells undergo several more

cell divisions Cell division is the process by which a parent cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukaryotes, there are ...

while at the same time upregulating survival genes such as

Bcl-xL B-cell lymphoma-extra large (Bcl-xL), encoded by the BCL2-like 1 gene, is a transmembrane molecule in the mitochondria. It is a member of the Bcl-2 family of proteins, and acts as an anti-apoptotic protein by preventing the release of mitochondr ...

, acquiring and storing large amounts of

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in fr ...

, ramping up the synthesis of

hemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyt ...

and other erythroid genes (in large part a GATA-1 dependent process that is augmented by the EpoR signaling) and decreasing in cell size, eventually removing their nuclei and being released into the bloodstream as a

reticulocyte Reticulocytes are immature red blood cells (RBCs). In the process of erythropoiesis (red blood cell formation), reticulocytes develop and mature in the bone marrow and then circulate for about a day in the blood stream before developing into ma ...

. There are several Nucleoli on the nucleus and it occupies most of the cell volume. the chromatins are consist of a network of fine red pink strands. The distinguished feature of pro erythroblast to its corresponding myeloblast in granulocytic series is that it carries more basophilic peripheral cytoplasm.

"Pronormoblast" vs. "proerythroblast"

Some sources consider the terms "pronormoblast" and "proerythroblast" to be

synonyms A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

. However, other sourcesProerythroblast

Dorland's Medical Dictionary ''Dorland's'' is the brand name of a family of medical reference works (including dictionaries, spellers and word books, and spell-check software) in various media spanning printed books, CD-ROMs, and online content. The flagship products are '' ...

consider "proerythroblast" to be a parent term, divided into the following two categories: * "pronormoblast" - normal development * "promegaloblast" - abnormal development

References

External links

* - "Bone Marrow and Hemopoiesis: bone marrow smear, erythroblast series with proerythroblast" * *
Image and description at purdue.edu

(

pernicious anemia Pernicious anemia is a type of vitamin B12 deficiency anemia, a disease in which not enough red blood cells are produced due to the malabsorption of vitamin B12. Malabsorption in pernicious anemia results from the lack or loss of intrinsic fa ...

)
Interactive image at usuarios.lycos.es

Blood cells {{Improve categories, date=June 2020