Reticulocytes

Reticulocytes are red blood cells that are still developing. in mammals, reticulocytes do not have a cell nucleus. They are called reticulocytes because of a reticular (mesh-like) network of ribosomal RNA that becomes visible under a microscope with certain stains such as new methylene blue and Romanowsky stain.  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 mature red blood cells.  These red blood cells move oxygen from your lungs to every cell in your body.

The normal fraction of reticulocytes in the blood depends on the clinical situation but is usually 0.5% to 2.5% in adults and 2% to 6% in infants. Calculating the reticulocyte production index is an important step in understanding whether or not the reticulocyte count is appropriate to the situation. 

Counting of Reticulocyte in circulating blood is an important tool in clinical hematology. The no of Reticulocytes in circulating blood reflects the erythropoietic activity of Bone Marrow. The nos of reticulocytes are used to classify & monitor the therapy of Anemia. Moreover, they are also useful for cancer patients since Anemia is one of the most frequent side effects of Anticancer Therapy.  

Conventional Manual Method for Reticulocyte studies involves Light Microscopy using supravital Dyes like New Methylene Blue or brilliant cresyl blue.   The Nucleic Acid material present in cells will get precipitated as dark blue network of reticulum.  Then the blood smear is examined under light microscopy. Counting of 2000 cells are recommended by the guide line of CLSI H44-A2 as routine method. The manual method is time consuming, labor intensive which requires expertise in identifying Reticulocytes by microscopy. However, the errors reported by many editorials are ranging between 20 to 40% for which the automated systems for the same are in great demand these days. 

To accurately measure reticulocyte counts, automated hematology analyzers uses a combination of laser excitation, detectors and a fluorescent dye (such as titan yellow or polymethine) or even traditional stains like NMB that marks RNA and DNA . These methods give quick and easy enumeration of Reticulocytes from Whole Blood sample.