Related Experiment Videos
A semithin light microscopic study of peritoneal cells of the mouse embryo
1Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan.
Abstract:
Using semithin plastic sections, sequential changes in the mouse peritoneal cells during their intrauterine life were observed by light microscopy. At 11-13 days of gestation, the peritoneal cavity contained a small number of free mononuclear cells, singly scattered. Most of them were 9 to 12 micron in cell diameter, and the N-C (nucleocytoplasmic) ratio was smaller than 0.7. The cytoplasm contained large phagocytic vacuoles, and long processes extended from the cell surface. These cells were considered mature macrophages. After 15 days, the peritoneal cavity contained small-sized mononuclear cells in addition to mature macrophages. The small mononuclear cells were 5-10 micron in cell diameter, and formed the major cell type at this time. The cytoplasm contained occasional small vesicles but no phagocytic vacuoles. The small mononuclear cells showed a larger N-C ratio, 0.8-1.7. In 18-day-old fetuses, the peritoneal cells consisted of mononuclear cells, 79.5%, and mast cells, 20.5%. During the initial 18 days of embryonic life, small lymphocytes, neutrophils and eosinophils were not contained in the mouse peritoneal space.
Insights
Mouse peritoneal cells transform during development. Early macrophages mature, and by day 15, smaller mononuclear cells become dominant, indicating significant intrauterine cellular changes.
Area of Science:
- Developmental Biology
- Immunology
- Cell Biology
Background:
- The peritoneal cavity's cellular composition during embryonic development is crucial for understanding immune system maturation.
- Previous studies have not fully detailed the sequential changes in mouse peritoneal cells in utero.
Purpose of the Study:
- To investigate the sequential changes in mouse peritoneal cells during intrauterine life.
- To characterize the morphology and prevalence of different peritoneal cell types during embryonic development.
Main Methods:
- Light microscopy was used to examine semithin plastic sections of mouse peritoneal cells.
- Cells were analyzed at various gestational ages (11-18 days) to observe sequential changes.
Main Results:
- At 11-13 days gestation, mature macrophages (9-12 micron, N-C ratio <0.7) with phagocytic vacuoles were observed.
- After 15 days, smaller mononuclear cells (5-10 micron, N-C ratio 0.8-1.7) became the predominant cell type.
- By 18 days, peritoneal cells comprised 79.5% mononuclear cells and 20.5% mast cells; lymphocytes, neutrophils, and eosinophils were absent.
Conclusions:
- Mouse peritoneal cavity undergoes significant cellular differentiation during intrauterine development.
- Macrophages are present early, with a distinct population of smaller mononuclear cells emerging later in gestation.
- The peritoneal cavity is initially populated by macrophages and mast cells, with other immune cells absent during the first 18 days of embryonic life.