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Primary Microglia Isolation from Mixed Glial Cell Cultures of Neonatal Rat Brain Tissue
Published on: August 15, 2012
Development of microglia in the postnatal rat hippocampus
1Department of Cell Biology and Physiology, Universitat Autònoma de Barcelona, Spain. i.dalmau@cc.uab.es
Abstract:
During the prenatal development of the hippocampus, microglial cell precursors progressively occur in all subfields in accordance with known ontogenetic gradients of the region (Dalmau et al., J. Comp. Neurol. 1997a;377:70-84). The present study follows the regional distribution of these microglial cell precursors and their morphological differentiation in the rat hippocampus from birth to postnatal (P) day 18. The results demonstrate that the cellular differentiation and the subregional distribution of microglia follow the specific developmental gradients of the different parts of Ammon's horn and the dentate gyrus. Microglial cell distribution in the dentate gyrus is thus delayed compared with that in Ammon's horn. The appearance of microglia in the hippocampal subregions and differentiation of cell precursors into adult microglia occur earlier at temporal levels than at septal levels. Distribution of microglial cells follows an outside-to-inside pattern from the hippocampal fissure to the main cell layers in either Ammon's horn or the dentate gyrus. Meanwhile, the resident microglial cells located in the stratum oriens and dentate hilus at birth also increase in number and gradually disperse throughout the whole tissue of the two layers with age. In Ammon's horn, microglial differentiation occurs earlier in CA3 than in CA1. In the dentate gyrus, microglia appear earlier in relation to the external limb than to the internal limb, largely following a lateral-to-medial gradient. The differentiation and appearance of microglia in the various hippocampal and dentate subregions often correspond to the developmental stage of intrinsic and extrinsic afferent nerve fiber projections. Finally, in both Ammon's horn and the dentate gyrus, cells resembling reactive microglia are also observed and, in particular, in the perforant path projections from P9 to P18, suggesting their participation not only in phagocytosis of dead cells but also in axonal elimination and/or fiber reorganization.
Insights
Microglia precursors in the developing rat hippocampus follow specific spatial and temporal gradients, appearing earlier in Ammon's horn than the dentate gyrus. These cells differentiate and distribute according to neurodevelopmental patterns, suggesting roles in axonal reorganization.
Area of Science:
- Neuroscience
- Developmental Biology
- Cell Biology
Background:
- Microglial cell precursors are present during prenatal hippocampal development.
- Their distribution follows known ontogenetic gradients within the hippocampus.
Purpose of the Study:
- To investigate the regional distribution and morphological differentiation of microglial cell precursors in the rat hippocampus from birth to postnatal day 18.
- To correlate microglial development with hippocampal structural and functional maturation.
Main Methods:
- Tracking microglial cell distribution and morphology in rat hippocampus from birth to P18.
- Analyzing spatial and temporal patterns of microglial appearance and differentiation across hippocampal subfields.
Main Results:
- Microglial differentiation and distribution in the hippocampus follow specific developmental gradients, with earlier appearance in Ammon's horn than the dentate gyrus.
- Temporal regions show earlier microglial development than septal regions.
- Distribution follows an outside-to-inside pattern, and reactive microglia are observed, particularly in perforant path projections.
Conclusions:
- Microglial development in the hippocampus is tightly linked to regional ontogenetic gradients and afferent nerve fiber projections.
- Microglia play roles beyond phagocytosis, including axonal elimination and fiber reorganization during development.
