Development, Differentiation, and Maturation of Macrophages in the Fetal Mouse Liver

Abstract

Primitive macrophages emerged in the sinusoidal lumen of the fetal mouse liver at 10 days of gestation before the initiation of hepatic hematopoiesis and matured into fetal macrophages. In the culture of cell suspensions from the fetal liver with LP3-conditioned medium, monocyte colonies were formed, but monocytopoiesis was poor in the early stage of hepatic hematopoiesis in vivo. In the culture of cell suspensions obtained from the fetal liver at 10 days of gestation on the monolayer of a mouse bone marrow stromal cell line, ST2, primitive/fetal macrophage colonies were formed before the development of monocyte/macrophage colonies and showed differentiation of primitive macrophages into fetal macrophages without passing through the stage of promonocytes and monocytes. At this time, the fetal cardiovascular system was connected with the vitelline vein just before the formation of the liver. With the progress of gestation, a monocytic cell series was observed to develop and form a monocyte/macrophage population. This was confirmed by in vitro studies with an LP3-conditioned medium and on a monolayer of ST2. Thus, it appears that there exist two different macrophage populations, a primitive/fetal macrophage population and a monocyte/macrophage population in hepatic hematopoiesis. It also appears that fetal macrophages are differentiated from primitive macrophages which are colonized into the fetal liver from the yolk sac or which develop in loco, presumably from hematopoietic stem cells.

Hepatic Extramedullary Hematopoiesis and Macrophages in the Adult Mouse: Histometrical and Immunohistochemical Studies

“…We found erythroblasts clustered around the sinusoidal macrophages. In adult livers, sinusoidal macrophages are distributed primarily in the peripheral region of hepatic lobules [Naito et al, 1990]. As shown in figure 4 a, the same results were obtained in the F4/80-immunostained sections.…”

Supporting cells as phagocytes in the olfactory epithelium after bulbectomy

“…Fetal immature macrophages are observed in the subepidermal mesenchyme in rats at embryonic day 12, and it is reported that macrophages in the resident population possess phagocytic vesicles in the cytoplasm at embryonic day 18 (Takahashi et al, 1983). Monocytes appear in the blood at embryonic day 17 in mice, and monocyte-derived macrophages show peroxidase activity at the end of the embryonic period (Naito et al, 1990). In our study, macrophages were present in newborn mice and phagocytized dying olfactory neurons.…”

Expression of the metastasis-associatedmts1 gene during mouse development

“…But in vitro studies indicate that not only the yolk sac but also the embryo itself exhibits hematopoietic precursors which have the potential to differentiate into myeloid cells (Huang et al, 1994;Cumano et al, 1996). Nevertheless, the first appearance and clonal proliferation of immature macrophages have been described in the blood islands of mouse and rat yolk sac around day 9 (Cline and Moore, 1972;Takahashi et al, 1989;Naito et al, 1990a), and after the connection between the vitelline vessels and the embryonic cardiovascular system around fetal day 10, the first mature fetal macrophages were visible throughout embryonic mesenchymal tissue (Takahashi et al, 1989, Naito et al, 1990b). As we described here, Mts1-expressing macrophages were first noted 2 days later, around day 12 of gestation.…”