The liver hemopoietic environment: II. Peroxidase reactive mouse fetal liver hemopoietic cells

Abstract

Through the combined use of peroxidase cytochemistry and examination at the ultrastructural level, the present study has identified liver hemopoietic foci containing three forms of erythropoietic cells, two forms of myelopoietic cells, and a population of peroxidase nonreactive cells within the extravascular compartments of mouse fetal liver. The nonreactive cells were 10 micron in diameter, displayed no peroxidase activity and were designated type I cells. This cell had an irregular nucleus, small profiles of rough endoplasmic reticulum (RER), a considerable population of monoribosomes and a few polyribosomes. The incidence of this cell type decreased significantly from 50% at 12 days gestation to approximately 10% of the hemopoietic cells at 17 days gestation. Type I cells could not be classified into a hemopoietic lineage and may represent undifferentiated hemopoietic stem cells. Three forms of erythropoietic cells, designated types II, III, and IV, were identified. These cells had a diffuse cytoplasmic peroxidase reaction, no peroxidase positive membrane-bound organelles, and were approximately 7 micron in diameter. They corresponded to the more classically defined proerythroblast, polychromatophilic erythroblast, and nucleated normoblast, respectively. Types II and III had moderate cytoplasmic reactions, whereas type III, in addition, had a slight nuclear reaction. Type IV cells had a very dense cytoplasmic reaction but no nuclear reaction. Of the myelopoietic cells detected, one form had a slightly reactive Golgi and a few reactive granules. The other form possessed a clearly positive nuclear envelope (NE), RER, Golgi, and a population of reactive granules. The phagocytic sinusoidal lining cells (Kupffer cells) were peroxidase negative in contrast to similar cells in the rat. A population of peroxidase-positive granules was detected in fetal liver developing hepatocytes at 17 days gestation and increased in number with age. The morphology and organization of these various cell types in the liver hemopoietic environment are discussed.

Effects of Interleukin-3 on Murine Fetal Liver Hemopoiesis in utero

“…Colo nies were classified as pure granulocyte (CFU-G): pure macrophage (CFU-M); CFU-GM: early crythroid de tected on day 7 (BFU-E): late erythroid detected on day 3 (CFU-E); megakaryocyte (CFU-Mcg); mixed (CFU-Mix) and mast-like (CFU-Mast). Apart from the morphological description of colonies [ 19], erythroid colonies were identified in samples stained with the pseudoperoxidase reaction for hemoglobin [20], and megakaryocyte colonies were confirmed by ultrastruc tural identification on isolated colonics (data not shown) ( …”

Cellular and Molecular Cascades during Liver Regeneration

“…12 During e9.5, the liver bud forms through the hepatic endoderm cells, known as hepatoblasts, and occupying the STM. 13,14 The STM provides the hepatic fibroblasts and stellate cells. 15 Starting at e10 until e15, liver bud gets invaded by hematopoietic cells as its development accelerates in order to become the main hematopoietic organ of the fetus.…”