Differential Cell Counts of Erythroid Precursors in Fetal Blood
Smears were prepared from approximately 50 (xl of blood samples from two fetuses per gilt, fixed with 100% methanol, and stained with Modified Wright-Giemsa stain (Sigma) for evaluation of erythrocyte and erythroid precursor numbers. Slides were evaluated by two investigators who were unaware of the day or treatment group represented by each slide. At least 100 cells/slide were counted under oil immersion (magnification, X1000) and classified as either basophilic erythroblast (BE), polychromatic erythroblast (PE), orthochromatic erythroblast (OE), or erythrocyte. buy ortho tri-cyclen
In addition, one smear from pooled Day 30 fetal blood samples for each gilt and two smears from individual Day 40 fetal blood samples for each gilt were stained with Accustain (Sigma) to differentiate reticulocytes and erythrocytes. Numbers of cells in the various classifications were converted to a percentage of the total, and the individual percentages of reticulocytes and erythrocytes were estimated from results of the reticulocyte stain evaluation. Results from the two observers were then averaged for statistical analysis. Because of a paucity of erythrocytes in Day 24 smears, no reticulocyte staining was done for that age. Thus, statistical analysis of reticulocytes included only Day 30 and Day 40. Estimates (by correlation analysis) of repeatability between observers were 0.38 for BE, 0.98 for PE, 0.96 for OE, 0.91 for reticulocytes, and 0.98 for erythrocytes.