Qualitative and cytometrical observations of mononuclear cells in the intraembryonic coelom of mouse embryo.

本实验采用半薄塑料切片，在光镜下观察了小鼠腹腔细胞和胚外体腔单个核细胞在宫内发育过程中的动态变化，得到以下结果.胚胎腹腔内有少量单个核细胞，单个散在分布。细胞质中含有大的吞噬空泡，长的细胞质突起从细胞表面延伸。单核细胞可以被认为是成熟的巨噬细胞。细胞直径大多为9 ~ 12 μ m，氮碳比小于0.7。在18日龄的胎儿中，腹膜细胞由单核细胞（79.5%）和肥大细胞（20.5%）组成。胚胎腹腔内不含小淋巴细胞和中性粒细胞.胚外体腔中的单核细胞妊娠11天前，胚外体腔与胚内体腔相连，外体腔中含有少量单核游离细胞。细胞核细长或肾形，细胞表面有许多绒毛状突起。细胞质中偶见小透明泡，但无吞噬泡。在第9天的卵黄管中，观察到与胚外游离细胞形态相似的单核细胞。卵黄囊单核细胞可能是胚胎腔中成熟巨噬细胞的最早可识别的前体细胞。

Using semithin plastic sections, sequential changes in the mouse peritoneal cells and mononuclear cells of extraembryonic coelom during their intrauterine life were observed by light microscopy, and following results were obtained.1. Peritoneal mononuclear free cells Embryonic peritoneal cavity contained a small number of free mononuclear cells, singly scattered. The cytoplasm contained large phagocytic vacuoles, and long cytoplasmic processes extended from the cell surface. The mononuclear cells could be considered mature macrophages. Most of them were 9 to 12 um in cell diameter, and N-C ratio was smaller than 0.7. In 18-day-old fetuses, the peritoneal cells consisted of mononuclear cells, 79.5%, and mast cells, 20.5%. Small lymphocytes and neutrophils were not contained in embryonic peritoneal cavity.2. Mononuclear cells in extraembryonic coelom Before 11 days of gestation, the extraembryonic coelom was continuous with the intraembryonic coelom, and the exocoel contained a small number of mononuclear free cells. These cells had an elongated or kidney-shaped nucleus and the cell surface showed many villous projection. The cytoplasm occasionally contained small lucent vesicles but no phagocytic vacuoles. In vitelline vessels at 9 days, mononuclear cells bearing a close morphological resemblance to extraembryonic free cells were observed. It is likely that yolk sac mononuclear cells are the earliest recognizable precursors of mature macrophages in embryonic cavities.