Mesoderm-derived cells proliferate in the embryonic central nervous system: confocal microscopy and three-dimensional...

Area of Science:

• Developmental biology
• Neuroscience
• Cell biology

Background:

• During embryonic development, mesodermal cells, including macrophages and endothelial cells, invade the neural tube.
• The origin and proliferative capacity of these intraneural cells are not fully understood.
• Understanding these cellular dynamics is crucial for comprehending neural tissue development.

Purpose of the Study:

• To investigate the proliferative capacity of mesoderm-derived macrophages and endothelial cells within the embryonic neural tube.
• To determine the origin of embryonic microglia.
• To characterize the morphology and interactions of intraneural macrophages.

Main Methods:

• Developed a double-immunofluorescence protocol using QH1 (endothelial cell/macrophage marker) and bromodeoxyuridine (S-phase marker).
• Utilized confocal laser scanning microscopy on thick microtome sections for cell labeling and analysis.
• Employed three-dimensional visualization of confocal data to analyze cell morphology and interactions.

Main Results:

• Intraneural endothelial cells showed a lower labeling index (10%) compared to extraneural endothelial cells (25%).
• Both spheroidal and ramified macrophages exhibited proliferative activity within the neural tissue.
• Ramified macrophages were observed to frequently contact capillary endothelial cells.

Conclusions:

• Proliferative activity of intraneural capillary endothelial cells is limited, particularly in sprouts.
• Embryonic microglia are likely derived from early invasive QH1-positive macrophages.
• Macrophages play a significant role in neural tissue development through proliferation and interaction with endothelial cells.