Morphological forms and localization of microglial cells in the developing human cerebellum

Area of Science:

• Neuroscience
• Developmental Biology
• Immunology

Background:

• Limited research exists on microglia in the developing human brain, leaving their function and location during this critical period largely unknown.
• Previous studies focused primarily on the earliest stages of fetal development, necessitating further investigation into later developmental phases.

Purpose of the Study:

• To investigate the participation and characteristics of microglial cells during human central nervous system development.
• To map the dynamic changes in microglial cell localization and morphology from fetal life through infancy.

Main Methods:

• Examination of brain tissue from 12 fetuses and infants (14 weeks gestation to 5 months post-birth) using immunological markers.
• Utilized Ricinus communis agglutinin-1 (RCA-1) to visualize microglia and endothelial cells, and anti-ferritin antiserum to specifically identify all microglial subpopulations (ameboid and ramified).
• Analyzed coronal sections of the cerebellum to track microglial cell presence, morphology, and distribution.

Main Results:

• Initially, only ameboid microglia were observed (14 weeks gestation) in the cerebellum, located in the germinal matrix and surrounding the dentate nucleus.
• As development progressed (up to 28 weeks gestation), ramified microglia increased, colonizing the cerebellar cortex and Purkinje cell layer.
• Post-birth, microglia predominantly appeared as ramified cells in the white matter, indicating a shift in localization and morphology.

Conclusions:

• Microglial cell localization and morphological transformations in the developing human brain are tightly correlated with specific developmental stages.
• This study provides a comprehensive timeline of microglial cell development in the human cerebellum, from early fetal stages to infancy.