Hematopoiesis in the embryonic mouse spleen. II. Alterations after phenylhydrazine administration to the mothers

Abstract

The effect of phenylhydrazine (PHZ) on the hematopoietic events in the embryonic spleen of C57Bl/6J mice was examined by light and electron microscopy. Following PHZ in injections to the mothers, the embryonic spleen revealed a marked increase in erythroid precursors, with a shift to mature cells. This phenomenon was part of a more generalized stimulation of erythorpoiesis, expressed by a shift to mature red cell precursors in the embryonic livers and an increase in the percentage of non-nucleated cells in the embryonic peripheral blood. Concomitantly stimulation of phagocytosis in the spleen of embryos in the early gestational days and increased vascularity were observed, and a later effect of granulocytopoietic stimulation. The effect on erythropoiesis in the embryonic spleen might be a sequence of erythropoietin stimulation, either in the mothers or the fetuses, due to anemia and hypoxia following PHZ injections.

Silencing of Aγ-Globin Gene Expression during Adult Definitive Erythropoiesis Mediated by GATA-1-FOG-1-Mi2 Complex Binding at the −566 GATA Site

“…Following induction, K562 cells display increased ␥-globin production (1,14,48,65). We also utilized nuclear extract prepared from the spleens of phenylhydrazinetreated transgenic mice, which express high levels of ␥-globin due to the reticulocytosis resulting from hemolytic anemia (18). Only a single footprint was observed in cells that do not express any ␥-globin or have a low expression level (CCRF-CEM, MEL 585, and uninduced K562 cells) ( Fig.…”

Increased Erythropoiesis in Embryonic Spleen of Polycythemic Mice

“…Only a few early red cell precur sors, defined as hemocytoblasts, were de tected at this stage of splenic development [5], Foci of mature red cell precursors were not seen until day 15. An attempt to stimu late erythropoiesis in the embryonic mouse spleen by injection of phenylhydrazine (PHZ) to the mothers resulted in a marked increase in erythroid precursors [7], The predominant type of cells in the spleen of 12th day em bryos of PHZ-injected mothers were the proerythroblasts, whereas in the 13th day PHZ spleens a marked shift to mature cells was noted. These results were interpreted as a consequence of erythropoietin stimulation, either in the mothers or in the fetuses, due to anemia and hypoxia caused by PHZ adminis tration.…”

“…The hemopoietic events dur ing embryonic development of C57B1/6J mice have been extensively investigated [4,11,15]. The production of red cell precursors in the embryonic mouse spleen was shown to begin with the appearance of the splenic rudi ment by the 12th day of gestation [5], Studies from this laboratory have shown that splenic erythropoiesis is indigenous to this organ and depends on the presence of erythropoietin, whether the experiments were carried out in vitro [1], or in vivo [7],The aim of the present study was to exam ine the erythropoietic events in the spleens of fetuses from polycythemic mothers. Since polycythemic mice are presumed to have low…”

Pattern of Liver Erythropoiesis in Embryos of Polycythemic Mice

“…It has been shown that induction of anemia by Phe nylhydrazine in pregnant mice caused a stim ulation of erythropoiesis in the embryonic liver, spleen, and peripheral blood [5], It was suggested that this stimulation might be in duced by erythropoietin produced either by the mother or by the fetus as a response to anemia [5]. In our previous study [10] we…”